Transmission device and transmission method

ABSTRACT

A transmission device comprising: a weighting circuitry which, in operation, generates transmission signals of n streams (n is an integer of 3 or more) by weighting modulated signals of the n streams using a predetermined fixed precoding matrix; a phase changing circuitry which, in operation, regularly changes each phase of a symbol series included in each of the transmission signals of the n streams; and a transmitter which, in operation, transmits the transmission signals of the n streams from different antennas, the phases of each of the transmission signals of the n streams being changed in each symbol, wherein the transmission signal of an i-th stream has an m i  kind of phase change value y i (t) (i is an integer between 1 and n (inclusive), 0≤y i &lt;2π, and m i  is set in each stream, t is an integer of 0 or more, and indicates a symbol slot), and the phase changing circuitry changes the phase in one or more u (u=m 1 ×m 2 × . . . ×m n ) symbol periods using all patterns of a set of phase change values y i (t) different from each other in each symbol.

BACKGROUND 1. Technical Field

The present disclosure relates to a transmission device and a receptiondevice for conducting communication using a multi-antenna.

2. Description of the Related Art

Conventionally, for example, MIMO (Multiple-Input Multiple-Output) iswell known as a communication method using a multi-antenna. Inmulti-antenna communication typified by MIMO, pieces of transmissiondata of a plurality of series are modulated, and each modulated signalis transmitted from a different antenna simultaneously to increase thetransmission speed of data.

FIG. 1 illustrates a configuration example of a transmission andreception device having two transmit antennas, two receive antennas, andtwo transmission modulated signals (two transmission streams). In thetransmission device, encoded data is interleaved, the interleaved datais modulated, and frequency conversion and the like is performed togenerate transmission signals, and the transmission signals aretransmitted from antennas. A scheme simultaneously transmittingdifferent modulated signals from different transmit antennas at anidentical frequency is a spatial multiplexing MIMO scheme.

At this point, PTL 1 proposes a transmission device provided with adifferent interleave pattern for each transmit antenna. That is, thetransmission device in FIG. 1 is provided with two different interleavepatterns having two interleaves (πa and πb) different from each other.In the reception device, as described in NPLs 1 and 2, reception qualityis improved by iteratively performing a detection method (a MIMOdetector in FIG. 1) in which a soft value is used.

A models for an actual propagation environment in wireless communicationincludes an NLOS (non-line of sight) environment typified by a Rayleighfading environment and an LOS (line of sight) environment typified by aRician fading environment. The transmission device transmits a singlemodulated signal, and the reception device performs a maximal ratiocombining on the signals received by a plurality of antennas anddemodulates and decodes the signals obtained by the maximal ratiocombining. Therefore, the excellent reception quality can be achieved inthe LOS environment, particularly in the environment having a largeRician factor that indicates a ratio of received power of a direct waveto received power of a scattered wave. However, depending on atransmission scheme (for example, a spatial multiplexing MIMO system),there occurs a problem that the reception quality degrades when theRician factor increases. (see NPL 3)

FIG. 2 illustrates an example of a simulation result of a BER (Bit ErrorRate) characteristic (a vertical axis indicates BER while a horizontalaxis indicates a SNR (Signal-to-Noise power Ratio)) when data encoded byLDPC (Low-Density Parity-Check) codes is transmitted through a 2×2 (twotransmit antennas and two receive antennas) spatial multiplexing MIMOsystem in the Rayleigh fading environment and the Rician fadingenvironment with the Rician factors K of 3, 10, and 16 dB. FIG. 2Aillustrates the BER characteristic of Max-log-APP (A PosterioriProbability) without performing the iterative detection (see NPLs 1 and2), and FIG. 2B illustrates the BER characteristic of Max-log-APP withthe iterative detection (five iterations) (see NPLs 1 and 2). As isclear from FIG. 2, regardless of the iterative detection, the receptionquality degrades in the spatial multiplexing MIMO system when the Ricianfactor increases. Thus, it is clear that the problem in that “thereception quality degrades when the propagation environment isstabilized in the spatial multiplexing MIMO system”, which does notexist in the conventional single modulation signal transmission system,is generated in the spatial multiplexing MIMO system.

Broadcasting or multicast communication is service necessary to adapt tovarious propagation environments because a broadcasting station or abase station simultaneously transmits information to many terminals, andthe LOS environment exists obviously in the radio propagationenvironment between a receiver owned by a user and the broadcastingstation. When the spatial multiplexing MIMO system is used in thebroadcasting or multicast communication, possibly the receiver generatesa phenomenon in which the service can hardly be received due to thedegradation of the reception quality although received field strength ishigh. That is, when the spatial multiplexing MIMO system is used in thebroadcasting or multicast communication, there is a demand fordevelopment of the MIMO system in which a certain degree of receptionquality is obtained in both the NLOS environment and the LOSenvironment.

NPL 4 describes a method for selecting a codebook (a precoding matrix(also referred to as a precoding weight matrix)) used in precoding fromfeedback information transmitted from a communication partner. However,NPL 4 does not disclose a method for performing the precoding in asituation in which the feedback information can hardly be acquired fromthe communication partner like the broadcasting or multicastcommunication.

On the other hand, NPL 5 discloses a method for switching the precodingmatrix over time. The method can be applied even if no feedbackinformation is available. NPL 5 discloses that a unitary matrix is usedas the matrix used in the precoding and that the unitary matrix isswitched at random. However, NPL 5 does not disclose a method applicableto the degradation of the reception quality in the LOS environment, butNPL 5 describes the simply random switching. NPL 5 describes neither aprecoding method for improving the degradation of the reception qualityin the LOS environment, nor a method for structuring the precodingmatrix.

PTL 2 discloses a specific method for changing the precoding matrix inthe case that two streams are subjected to the precoding to transmit themodulated signals from two antennas.

CITATION LIST Patent Literatures

PTL 1: International Patent Publication No. 2005/050885

PTL 2: Japanese Patent Application No. 2010-177310

Non-Patent Literatures

-   NPL 1: “Achieving near-capacity on a multiple-antenna channel” IEEE    Transaction on communications, vol. 51, no. 3, pp. 389-399, March    2003.-   NPL 2: “Performance analysis and design optimization of LDPC-coded    MIMO OFDM systems” IEEE Trans. Signal Processing., vol. 52, no. 2,    pp. 348-361, February 2004.-   NPL 3: “BER performance evaluation in 2×2 MIMO spatial multiplexing    systems under Rician fading channels,” IEICE Trans. Fundamentals,    vol. E91-A, no. 10, pp. 2798-2807, October 2008.-   NPL 4: D. J. Love, and R. W. heath, Jr., “Limited feedback unitary    precoding for spatial multiplexing systems,” IEEE Trans. Inf.    Theory, vol. 51, no. 8, pp. 2967-2976, August 2005.-   NPL 5: “Turbo space-time codes with time varying linear    transformations,” IEEE Trans. Wireless communications, vol. 6, no.    2, pp. 486-493, February 2007.-   NPL 6: DVB Document A122, Framing structure, channel coding and    modulation for a second generation digital terrestrial television    broadcasting system (DVB-T2), June 2008.-   NPL 7: L. Vangelista, N. Benvenuto, and S. Tomasin, “Key    technologies for next-generation terrestrial digital television    standard DVB-T2,” IEEE Commun. Magazine, vo. 47, no. 10, pp.    146-153, October 2009.-   NPL 8: X. Zhu and R. D. Murch, “Performance analysis of maximum    likelihood detection in a MIMO antenna system,” IEEE Trans. Commun.,    vo. 50, no. 2, pp. 187-191, February 2002.-   NPL 9: “Likelihood function for QR-MLD suitable for soft-decision    turbo decoding and its performance,” IEICE Trans. Commun., vol.    E88-B, no. 1, pp. 47-57, January 2004.-   NPL 10: B. M. Hochwald and S. ten Brink, “Achieving near-capacity on    a multiple-antenna channel,” IEEE Trans. Commun., vo. 51, no. 3, pp.    389-399, March 2003.-   NPL 11: T. Ohgane, T. Nishimura, and Y. Ogawa, “Application of space    division multiplexing and those performance in a MIMO channel,”    IEICE Trans. Commun., vo. 88-B, no. 5, pp. 1843-1851, May 2005.-   NPL 12: “Advanced signal processing for PLCs: Wavelet-OFDM,” Proc.    of IEEE International symposium on ISPLC 2008, pp. 187-192, 2008.

However, in the above cited documents, there is no description that thespecific method for changing the precoding matrix in the case that atleast three streams are subjected to the precoding to transmit themodulated signals from at least three antennas.

SUMMARY

One non-limiting and exemplary embodiment provides a transmission devicethat can improve the degradation of the reception quality in the LOSenvironment in the case that at least three streams are subjected to theprecoding to transmit the modulated signals from at least threeantennas.

In one general aspect, the techniques disclosed here feature: atransmission device that transmits transmission signals of n streams (nis an integer of 3 or more) from different antennas, the transmissiondevice includes: a weighting circuitry which, in operation, generatesthe transmission signals of the n streams by weighting modulated signalsof the n streams using a predetermined fixed precoding matrix; and aphase changing circuitry which, in operation, regularly changes eachphase of the transmission signals of the n streams. At this point, whenvalue a_(ki) that can be taken by phase change value y_(i)(t) in orderof generating a symbol of i-th stream (i is an integer between 0 and n−1(inclusive)) is an m_(i) kind (0≤a_(ki)<2π, k_(i) is an integer between0 and m_(i) (inclusive), and m_(i) is set in each stream), the phasechanging circuitry sets each of all patterns that can be taken by an nset of a_(ki) [a_(ki)]n to one of symbol number u (u is an integerbetween 0 and M (inclusive), and M=m₀×m₁× . . . ×m_(n-1)).

Additional benefits and advantages of the disclosed embodiments willbecome apparent from the specification and drawings. The benefits and/oradvantages may be individually obtained by the various embodiments andfeatures of the specification and drawings, which need not all beprovided in order to obtain one or more of such benefits and/oradvantages.

It should be noted that general or specific embodiments may beimplemented as a system, a method, an integrated circuit, a computerprogram, a storage medium, or any selective combination thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a configuration example of a transmission andreception device in a spatial multiplexing MIMO transmission system;

FIG. 2A illustrates an example of a BER characteristic;

FIG. 2B illustrates an example of the BER characteristic;

FIG. 3 illustrates a configuration example of the transmission andreception device in the spatial multiplexing MIMO transmission system;

FIG. 4 illustrates an example of a frame structure;

FIG. 5 illustrates a configuration example of a transmission deviceduring application of a phase changing method;

FIG. 6 illustrates a configuration example of the transmission deviceduring the application of the phase changing method;

FIG. 7A illustrates an example of the frame structure;

FIG. 7B illustrates an example of the frame structure;

FIG. 8A illustrates an example of the phase changing method;

FIG. 8B illustrates an example of the phase changing method;

FIG. 9 illustrates a configuration example of a reception device;

FIG. 10 illustrates an example of the frame structure on a time axis ofthe transmission device;

FIG. 11 illustrates an example of a transmit antenna and a receiveantenna;

FIG. 12A illustrates an example of a weighting unit and a phase changingunit;

FIG. 12B illustrates an example of the frame structure;

FIG. 13 illustrates a configuration example of the reception device;

FIG. 14 illustrates an example of a state in which a candidate signalpoint is obtained;

FIG. 15 illustrates an example of the state in which the candidatesignal point is obtained;

FIG. 16 illustrates an example of the state in which the candidatesignal point is obtained;

FIG. 17 illustrates a specific example of a phase change value;

FIG. 18 illustrates a specific example of the phase change value;

FIG. 19 illustrates a configuration example of the transmission devicewhen an OFDM scheme is used;

FIG. 20 illustrates a configuration example of the transmission devicewhen the OFDM scheme is used;

FIG. 21 illustrates a configuration example of the transmission devicewhen the OFDM scheme is used;

FIG. 22A illustrates an example of a symbol rearranging method;

FIG. 22B illustrates an example of the symbol rearranging method;

FIG. 22C illustrates an example of the symbol rearranging method;

FIG. 23A illustrates an example of the symbol rearranging method;

FIG. 23B illustrates an example of the symbol rearranging method;

FIG. 23C illustrates an example of the symbol rearranging method;

FIG. 24A illustrates an example of the symbol rearranging method;

FIG. 24B illustrates an example of the symbol rearranging method;

FIG. 24C illustrates an example of the symbol rearranging method;

FIG. 25A illustrates an example of the symbol rearranging method;

FIG. 25B illustrates an example of the symbol rearranging method;

FIG. 25C illustrates an example of the symbol rearranging method;

FIG. 26A illustrates an example of the symbol rearranging method;

FIG. 26B illustrates an example of the symbol rearranging method;

FIG. 26C illustrates an example of the symbol rearranging method;

FIG. 27 illustrates a configuration example of the transmission device;

FIG. 28 illustrates a configuration example of the transmission device;

FIG. 29 illustrates configuration examples of the weighting unit and thephase changing unit;

FIG. 30 illustrates an example of the frame structure on the time axisof the transmission device;

FIG. 31 illustrates examples of the transmit antenna and receiveantenna;

FIG. 32A illustrates an example of the weighting unit and phase changingunit;

FIG. 32B illustrates an example of the frame structure;

FIG. 33 illustrates a configuration example of the reception device;

FIG. 34 illustrates an example of the state in which the candidatesignal point is obtained;

FIG. 35 illustrates an example of the state in which the candidatesignal point is obtained;

FIG. 36 illustrates an example of the state in which the candidatesignal point is obtained;

FIG. 37 illustrates a specific example of the phase change value;

FIG. 38 illustrates a specific example of the phase change value;

FIG. 39 illustrates a configuration example of the transmission devicewhen the OFDM scheme is used;

FIG. 40 illustrates a configuration example of the transmission devicewhen the OFDM scheme is used;

FIG. 41 illustrates a configuration example of the transmission devicewhen the OFDM scheme is used;

FIG. 42A illustrates an example of the symbol rearranging method;

FIG. 42B illustrates an example of the symbol rearranging method;

FIG. 42C illustrates an example of the symbol rearranging method;

FIG. 42D illustrates an example of the symbol rearranging method;

FIG. 43A illustrates an example of the symbol rearranging method;

FIG. 43B illustrates an example of the symbol rearranging method;

FIG. 43C illustrates an example of the symbol rearranging method;

FIG. 43D illustrates an example of the symbol rearranging method;

FIG. 44A illustrates an example of the symbol rearranging method;

FIG. 44B illustrates an example of the symbol rearranging method;

FIG. 44C illustrates an example of the symbol rearranging method;

FIG. 44D illustrates an example of the symbol rearranging method;

FIG. 45A illustrates an example of the symbol rearranging method;

FIG. 45B illustrates an example of the symbol rearranging method;

FIG. 45C illustrates an example of the symbol rearranging method;

FIG. 45D illustrates an example of the symbol rearranging method;

FIG. 46A illustrates an example of the symbol rearranging method;

FIG. 46B illustrates an example of the symbol rearranging method;

FIG. 46C illustrates an example of the symbol rearranging method;

FIG. 46D illustrates an example of the symbol rearranging method;

FIG. 47 illustrates an example of a configuration performing a precodingmethod;

FIG. 48 illustrates an example of the configuration performing theprecoding method;

FIG. 49 illustrates an example of the configuration performing theprecoding method;

FIG. 50 illustrates an example of the configuration performing theprecoding method;

FIG. 51 illustrates an example of the configuration performing theprecoding method;

FIG. 52 illustrates an example of the configuration performing theprecoding method;

FIG. 53 illustrates an example of the configuration performing theprecoding method;

FIG. 54 illustrates an example of the configuration performing theprecoding method;

FIG. 55 illustrates an example of the configuration performing theprecoding method;

FIG. 56 illustrates an example of the configuration performing theprecoding method;

FIG. 57 illustrates an example of the configuration performing theprecoding method; and

FIG. 58 illustrates an example of the configuration performing theprecoding method.

DETAILED DESCRIPTION

Hereinafter, exemplary embodiments of the present disclosure will bedescribed in detail with reference to the drawings.

First Exemplary Embodiment

A transmission method, a transmission device, a reception method, and areception device according to a first exemplary embodiment will bedescribed in detail.

Outlines of transmission and decoding methods in a conventional spatialmultiplexing MIMO transmission system will be described prior to thedescription of the first exemplary embodiment.

FIG. 3 illustrates a configuration of an N_(t)×N_(r) spatialmultiplexing MIMO system. Information vector z is subjected to encodingand interleaving. Encoded bit vector u=(u₁, . . . , u_(Nt)) is acquiredas interleaving output, where u_(i)=(u_(i1), . . . , u_(iM)) (M is thenumber of transmission bits per symbol). Letting transmission vectors=(s₁, . . . , s_(Nt))^(T) leads to transmission signal s_(i)=map(u_(i))from transmit antenna #i, and the normalized transmission energy isexpressed by E{|s_(i)|²}=Es/Nt (E_(s) is total energy per channel).Letting y=(y₁, . . . , y_(Nr))^(T) expresses a received vector usingEquation (1).

$\begin{matrix}\lbrack {{Mathematical}{\mspace{11mu} \;}{formula}\mspace{14mu} 1} \rbrack & \; \\\begin{matrix}{y = ( {y_{1},\Lambda,y_{Nr}} )^{T}} \\{= {{H_{NtNr}s} + n}}\end{matrix} & {{Equation}\mspace{14mu} (1)}\end{matrix}$

Where H_(NtNr) is a channel matrix, n=(n₁, . . . , n_(Nr))^(T) is anoise vector, and n_(i) is i.i.d. complex Gaussian random noise with anaverage value of 0 and variance of σ². From a relationship betweentransmission and reception symbols induced to the receiver, aprobability for the received vector may be provided as amulti-dimensional Gaussian distribution as expressed by Equation (2).

$\begin{matrix}\lbrack {{Mathematical}{\mspace{11mu} \;}{formula}\mspace{14mu} 2} \rbrack & \; \\{{p( {yu} )} = {\frac{1}{( {2\; \pi \; \sigma^{2}} )^{N_{r}}}{\exp ( {{- \frac{1}{2\; \sigma^{2}}}{{y - {{Hs}(u)}}}^{2}} )}}} & {{Equation}\mspace{14mu} (2)}\end{matrix}$

At this point, a receiver that performs iterative decoding is consideredas illustrated in FIG. 3. The receiver includes an outersoft-in/soft-out decoder and a MIMO detector. The vector of alogarithmic likelihood ratio (L-value) in FIG. 1 is expressed byEquations (3) to (5).

$\begin{matrix}\lbrack {{Mathematical}{\mspace{11mu} \;}{formula}\mspace{14mu} 3} \rbrack & \; \\{{L(u)} = ( {{L( u_{1} )},\Lambda,{L( u_{N_{t}} )}} )^{T}} & {{Equation}\mspace{14mu} (3)} \\\lbrack {{Mathematical}{\mspace{11mu} \;}{formula}\mspace{14mu} 4} \rbrack & \; \\{{L( u_{i} )} = ( {{L( u_{i\; 1} )},\Lambda,{L( u_{iM} )}} )} & {{Equation}\mspace{14mu} (4)} \\\lbrack {{Mathematical}{\mspace{11mu} \;}{formula}\mspace{14mu} 5} \rbrack & \; \\{{L( u_{ij} )} = {\ln \frac{P( {u_{ij} = {+ 1}} )}{P( {u_{ij} = {- 1}} )}}} & {{Equation}\mspace{14mu} (5)}\end{matrix}$

<Iterative Detection Method>

Iterative detection of a MIMO signal in the N_(t)×N_(r) spatialmultiplexing MIMO system will be described below.

The logarithmic likelihood ratio of xu_(mn) is defined by Equation (6).

$\begin{matrix}\lbrack {{Mathematical}{\mspace{11mu} \;}{formula}\mspace{14mu} 6} \rbrack & \; \\{{L( {u_{mn}y} )} = {\ln \frac{P( {u_{mn} = {{+ 1}y}} )}{P( {u_{mn} = {{- 1}y}} )}}} & {{Equation}\mspace{14mu} (6)}\end{matrix}$

From Bayes' theorem, Equation (6) can be expressed as Equation (7).

$\begin{matrix}\lbrack {{Mathematical}{\mspace{11mu} \;}{formula}\mspace{14mu} 7} \rbrack & \; \\\begin{matrix}{{L( {u_{mn}y} )} = {\ln \frac{{P( {{yu_{mn}} = {+ 1}} )}{{P( {u_{mn} = {+ 1}} )}/{p(y)}}}{{P( {{yu_{mn}} = {- 1}} )}{{P( {u_{mn} = {- 1}} )}/{p(y)}}}}} \\{= {{\ln \frac{P( {u_{mn} = {+ 1}} )}{P( {u_{mn} = {- 1}} )}} + {\ln \frac{P( {{yu_{mn}} = {+ 1}} )}{P( {{yu_{mn}} = {- 1}} )}}}} \\{= {{\ln \frac{P( {u_{mn} = {+ 1}} )}{P( {u_{mn} = {- 1}} )}} +}} \\{{\ln \frac{\sum\limits_{U_{{mn},{+ 1}}}\; {{p( {yu} )}{p( {uu_{mn}} )}}}{\sum\limits_{U_{{mn},{- 1}}}\; {{p( {yu} )}{p( {uu_{mn}} )}}}}}\end{matrix} & {{Equation}\mspace{14mu} (7)}\end{matrix}$

Where U_(mn,±1)={u|u_(mn)=±1}. When approximating ln Σa_(j)˜max lna_(j), Equation (7) can be approximated by Equation (8). The abovesymbol “˜” means approximation.

$\begin{matrix}{\mspace{79mu} \lbrack {{Mathematical}{\mspace{11mu} \;}{formula}\mspace{14mu} 8} \rbrack} & \; \\{{L( {u_{mn}y} )} \approx {{\ln \frac{P( {u_{mn} = {+ 1}} )}{P( {u_{mn} = {- 1}} )}} + {\max\limits_{{Umn},{+ 1}}\{ {{\ln \; {p( {yu} )}} + {P( {uu_{mn}} )}} \}} - {\max\limits_{{Umn},{- 1}}\{ {{\ln \; {p( {yu} )}} + {P( {uu_{mn}} )}} \}}}} & {{Equation}\mspace{14mu} (8)}\end{matrix}$

P(u|u_(mn)) and ln P(u|u_(mn)) in Equation (8) are expressed byEquations (9), (10), and (11).

$\begin{matrix}\lbrack {{Mathematical}{\mspace{11mu} \;}{formula}\mspace{14mu} 9} \rbrack & \; \\\begin{matrix}{{P( {uu_{mn}} )} = {\prod\limits_{{({ij})} \neq {({nm})}}\; {P( u_{ij} )}}} \\{= {\prod\limits_{{({ij})} \neq {({nm})}}\frac{\exp ( \frac{u_{ij}{L( u_{ij} )}}{2} )}{{\exp ( \frac{L( u_{ij} )}{2} )} + {\exp ( \frac{L( u_{ij} )}{2} )}}}}\end{matrix} & {{Equation}\mspace{14mu} (9)} \\\lbrack {{Mathematical}{\mspace{11mu} \;}{formula}\mspace{14mu} 10} \rbrack & \; \\{{\ln \; {P( {uu_{mn}} )}} = {( {\sum\limits_{ij}\; {\ln \; {P( u_{ij} )}}} ) - {\ln \; {P( u_{mn} )}}}} & {{Equation}\mspace{14mu} (10)} \\\lbrack {{Mathematical}{\mspace{11mu} \;}{formula}\mspace{14mu} 11} \rbrack & \; \\\begin{matrix}{{\ln \; {P( u_{ij} )}} = {{\frac{1}{2}u_{ij}{P( u_{ij} )}} - {\ln \begin{pmatrix}{{\exp ( \frac{L( u_{ij} )}{2} )} +} \\{\exp ( {- \frac{L( u_{ij} )}{2}} )}\end{pmatrix}}}} \\{\approx {{\frac{1}{2}u_{ij}{L( u_{ij} )}} - {\frac{1}{2}{{L( u_{ij} )}}\mspace{14mu} {for}\mspace{14mu} {{L( u_{ij} )}}}} > 2} \\{= {{\frac{L( u_{ij} )}{2}}( {{u_{ij}{{sign}( {L( u_{ij} )} )}} - 1} )}}\end{matrix} & {{Equation}\mspace{14mu} (11)}\end{matrix}$

A logarithmic probability of the equation defined in Equation (2) isexpressed by Equation (12).

$\begin{matrix}\lbrack {{Mathematical}{\mspace{11mu} \;}{formula}\mspace{14mu} 12} \rbrack & \; \\{{\ln \; {P( {yu} )}} = {{{- \frac{N_{r}}{2}}{\ln ( {2\; \pi \; \sigma^{2}} )}} - {\frac{1}{2\; \sigma^{2}}{{y - {{Hs}(u)}}}^{2}}}} & {{Equation}\mspace{14mu} (12)}\end{matrix}$

Accordingly, from Equations (7) and (12), in MAP or APP (A PosterioriProbability), the a posteriori L-value is expressed by Equation (13).

$\begin{matrix}{\mspace{79mu} \lbrack {{Mathematical}{\mspace{11mu} \;}{formula}\mspace{14mu} 13} \rbrack} & \; \\{{L( {u_{mn}y} )} = {\ln \frac{\sum\limits_{U_{{mn},{+ 1}}}\; {\exp \{ {{{- \frac{1}{2\; \sigma^{2}}}{{y - {{Hs}(u)}}}^{2}} + {\sum\limits_{ij}\; {\ln \; {P( u_{ij} )}}}} \}}}{\sum\limits_{U_{{mn},{- 1}}}\; {\exp \{ {{{- \frac{1}{2\; \sigma^{2}}}{{y - {{Hs}(u)}}}^{2}} + {\sum\limits_{ij}\; {\ln \; {P( u_{ij} )}}}} \}}}}} & {{Equation}\mspace{14mu} (13)}\end{matrix}$

Hereinafter, this is referred to as iterative APP decoding. FromEquations (8) and (12), in the logarithmic likelihood ratio utilizingMax-Log approximation (Max-Log APP), the a posteriori L-value isexpressed by Equation (14).

$\begin{matrix}{\mspace{79mu} \lbrack {{Mathematical}{\mspace{11mu} \;}{formula}\mspace{14mu} 14} \rbrack} & \; \\{{L( {u_{mn}y} )} \approx {{\max\limits_{{Umn},{+ 1}}\{ {\Psi ( {u,y,{L(u)}} )} \}} - {\max\limits_{{Umn},{- 1}}\{ {\Psi ( {u,y,{L(u)}} )} \}}}} & {{Equation}\mspace{14mu} (14)} \\{\mspace{79mu} \lbrack {{Mathematical}{\mspace{11mu} \;}{formula}\mspace{14mu} 15} \rbrack} & \; \\{{\Psi ( {u,y,{L(u)}} )} = {{{- \frac{1}{2\; \sigma^{2}}}{{y - {{Hs}(u)}}}^{2}} + {\sum\limits_{ij}\; {\ln \; {P( u_{ij} )}}}}} & {{Equation}\mspace{14mu} (15)}\end{matrix}$

Hereinafter, this is referred to as iterative Max-log APP decoding.External information necessary for an iterative decoding system can beobtained by subtracting prior inputs from Equations (13) and (14).

<System Model>

FIG. 1 illustrates a basic configuration of a system related to thesubsequent description. The system in FIG. 1 is a 2×2 spatialmultiplexing MIMO system. There is an outer encoder for each of streamsA and B, and the two outer encoders are an identical LDPC encoder. Inthis case, the configuration in which the LDPC encoder is used as theouter encoder by way of an example. However, the error correction codingused in the outer encoder is not limited to the LDPC coding. The presentdisclosure may similarly be embodied using other pieces of errorcorrection coding such as turbo coding, convolutional coding, and LDPCconvolutional coding. The outer encoder is provided in each transmitantenna, but the outer encoder is not limited to the configuration inFIG. 1. Alternatively, a plurality of transmit antennas may be used, andonly one outer encoder may be used. Additionally, the outer encoders maybe provided more than the transmit antenna in number. Streams A and Bhave interleavers (π_(a) and π_(b)), respectively. In this case, themodulation scheme is set to 2^(h)-QAM (h bits are transmitted by onesymbol).

It is assumed that the receiver performs iterative detection of the MIMOsignal (iterative APP (or iterative Max-log APP) decoding). For example,it is assumed that an LDPC code is decoded by sum-product decoding.

FIG. 4 illustrates a frame structure, and the order of the interleavedsymbols. At this point, it is assumed that (i_(a), j_(a)), (i_(b),j_(b)) are represented by Equations (16) and (17).

[Mathematical formula 16]

(i _(a) ,j _(a))=π_(a)(Q _(ia,ja) ^(a))  Equation (16)

[Mathematical formula 17]

(i _(b) ,j _(b))=π_(b)(Ω_(ib,jb) ^(a))  Equation (17)

Where i^(a) and i^(b) indicate the order of the interleaved symbols,j^(a) and j^(b) indicate the bit positions (j^(a), j^(b)=1, . . . , h)in the modulation scheme, π^(a) and π^(b) indicate the interleavers forstreams A and B, and Ω^(a) _(ia,ja) and Ω^(b) _(ib,jb) indicate theorder of pieces of pre-interleaving data in streams A and B. FIG. 4illustrates the frame structure for i_(a)=i_(b).

<Iterative Decoding>

An iterative detection algorithms for sum-product decoding and MIMOsignal, which are used to decode an LDPC code of the receiver, will bedescribed in detail below.

Sum-Product Decoding

It is assumed that two-dimensional M×N matrix H={H_(mn)} is a checkmatrix for the LDPC code of a decoding target. Subsets A(m) and B(n) ofthe set [1, N]={1, 2, . . . N} are defined by Equations (18) and (19).

[Mathematical formula 18]

A(m)≡{n:H _(mn)=1}  Equation (18)

[Mathematical formula 19]

B(n)≡{m:H _(mn)=1}  Equation (19)

Where A(m) indicates a set of column indices of 1 in the m-th column ofcheck matrix H, and B(n) represents a set of row indices of 1 in then-th row of check matrix H. The sum-product decoding algorithm is asfollows.

Step A⋅1 (initialization): A prior value logarithmic ratio β_(mn) is setto 0 for all combinations (m, n) satisfying H_(mn)=1. Loop variable (thenumber of iterations) I_(sum)=is set to 1, and the maximum number ofloops is set to I_(sum,max).

Step A⋅2 (row processing): Using update Equations (20), (21), and (22),exterior value logarithmic ratio α_(mn) is updated for all combinations(m, n) satisfying H_(mn)=1 in the order of m=1, 2, . . . , M.

$\begin{matrix}{\mspace{79mu} \lbrack {{Mathematical}{\mspace{11mu} \;}{formula}\mspace{14mu} 20} \rbrack} & \; \\{\alpha_{mn} = {( {\prod\limits_{n^{\prime} \in {{A{(m)}}{\backslash n}}}\; {{sign}( {\lambda_{n^{\prime}} + \beta_{{mn}^{\prime}}} )}} ) \times {f( {\prod\limits_{n^{\prime} \in {{A{(m)}}{\backslash n}}}{f( {\lambda_{n^{\prime}} + \beta_{{mn}^{\prime}}} )}} )}}} & {{Equation}\mspace{14mu} (20)} \\{\mspace{79mu} \lbrack {{Mathematical}{\mspace{11mu} \;}{formula}\mspace{14mu} 21} \rbrack} & \; \\{\mspace{79mu} {{{sign}(x)} \equiv \{ \begin{matrix}1 & {x \geq 0} \\{- 1} & {x < 0}\end{matrix} }} & {{Equation}\mspace{14mu} (21)} \\{\mspace{79mu} \lbrack {{Mathematical}{\mspace{11mu} \;}{formula}\mspace{14mu} 22} \rbrack} & \; \\{\mspace{79mu} {{f(x)} \equiv {\ln \frac{{\exp (x)} + 1}{{\exp (x)} - 1}}}} & {{Equation}\mspace{14mu} (22)}\end{matrix}$

Where f indicates a Gallager function. A method for seeking λ_(n) isdescribed in detail later.

Step A⋅3 (column processing): Using Equation (23), exterior valuelogarithmic ratio β_(mn) is updated for all combinations (m, n)satisfying H_(mn)=1 in the order of n=1, 2, . . . , N.

$\begin{matrix}\lbrack {{Mathematical}{\mspace{11mu} \;}{formula}\mspace{14mu} 23} \rbrack & \; \\{\beta_{mn} = {\sum\limits_{m^{\prime} \in {{B{(n)}}\backslash m}}\; \alpha_{m^{\prime}n}}} & {{Equation}\mspace{14mu} (23)}\end{matrix}$

Step A⋅4 (calculation of logarithmic likelihood ratio): Logarithmiclikelihood ratio L_(n) for n∈[1,N] is obtained by Equation (24).

$\begin{matrix}\lbrack {{Mathematical}{\mspace{11mu} \;}{formula}\mspace{14mu} 24} \rbrack & \; \\{L_{n} = {{\sum\limits_{m^{\prime} \in {{B{(n)}}\backslash m}}\; \alpha_{m^{\prime}n}} + \lambda_{n}}} & {{Equation}\mspace{14mu} (24)}\end{matrix}$

Step A⋅5 (count of the number of iterations): if I_(sum)<I_(sum,max),I_(sum) is incremented, and processing returns to Step A⋅2. IfI_(sum)=I_(sum,max), the sum-product decoding in this round is finished.

The operation in one sum-product decoding is described above. Then theiterative detection of the MIMO signal is performed. In variables m, n,α_(mn), β_(mn), λ_(n), and L_(n) used in the above description for theoperation of the sum-product decoding, it is assumed that the variablesare indicated by m_(a), n_(a), φ^(a) _(mana), β^(a) _(mana), λ_(na), andL_(na) in stream A, and that the variables are indicated by m_(b),n_(b), α^(b) _(mbnb), β^(b) _(mbnb), λ_(nb), and L_(nb) in stream B.

<Iterative Detection of MIMO Signal>

A method for seeking λ_(n) in the iterative detection of the MIMO signalwill be described in detail.

Equation (25) holds from Equation (1).

$\begin{matrix}\lbrack {{Mathematical}\mspace{14mu} {formula}\mspace{14mu} 25} \rbrack & \; \\\begin{matrix}{{y(t)} = ( {{y_{1}(t)},{y_{2}(t)}} )^{T}} \\{= {{{H_{22}(t)}{s(t)}} + {n(t)}}}\end{matrix} & {{Equation}\mspace{14mu} (25)}\end{matrix}$

The following relational expressions hold from the frame structures inFIG. 4 and Equations (16) and (17).

[Mathematical formula 26]

n _(a)=Ω_(ia,ja) ^(a)  Equation (26)

[Mathematical formula 27]

n _(b)=Ω_(ib,jb) ^(b)  Equation (27)

Where n_(a),n_(b)∈[1, N]. Hereinafter, λ_(na), L_(na), λ_(nb), andL_(nb), where the number of iterations of iterative MIMO signaldetection is k, are indicated as λ_(k,na), L_(k,na), λ_(k,nb), andL_(k,nb).

Step B⋅1 (initial detection; k=0): In initial detection, λ_(0,na) andλ_(0,nb) are obtained by Equations (28), (29), and (30).

In iterative APP decoding:

$\begin{matrix}{\mspace{79mu} \lbrack {{Mathematical}\mspace{14mu} {formula}\mspace{14mu} 28} \rbrack} & \; \\{\lambda_{0,n_{X}} = {\ln \frac{\sum_{U_{0,n_{X},{+ 1}}}{\exp \{ {{- \frac{1}{2\sigma^{2}}}{\begin{matrix}{{y( i_{X} )} -} \\{{H_{22}( i_{X} )}{s( {u( i_{X} )} )}}\end{matrix}}^{2}} \}}}{\sum_{U_{0,n_{X},{- 1}}}{\exp \{ {{- \frac{1}{2\sigma^{2}}}{\begin{matrix}{{y( i_{X} )} -} \\{{H_{22}( i_{X} )}{s( {u( i_{X} )} )}}\end{matrix}}^{2}} \}}}}} & {{Equation}\mspace{14mu} (28)}\end{matrix}$

In iterative Max-log APP decoding:

$\begin{matrix}{\mspace{79mu} \lbrack {{Mathematical}\mspace{14mu} {formula}\mspace{14mu} 29} \rbrack} & \; \\{\lambda_{0,n_{X}} = {{\max\limits_{U_{0,n_{X},{+ 1}}}\{ {\Psi ( {{u( i_{X} )},{y( i_{X} )}} )} \}} - {\max\limits_{U_{0,n_{X},{- 1}}}\{ {\Psi ( {{u( i_{X} )},{y( i_{X} )}} )} \}}}} & {{Equation}\mspace{14mu} (29)} \\{\mspace{79mu} \lbrack {{Mathematical}\mspace{14mu} {formula}\mspace{14mu} 30} \rbrack} & \; \\{\mspace{79mu} {{\Psi ( {{u( i_{X} )},{y( i_{X} )}} )} = {{- \frac{1}{2\sigma^{2}}}{{{y( i_{X} )} - {{H_{22}( i_{X} )}{s( {u( i_{X} )} )}}}}^{2}}}} & {{Equation}\mspace{14mu} (30)}\end{matrix}$

Where X=a, b. The number of iterations of the iterative detection of theMIMO signal I_(mimo) is set to 0, and the maximum number of iterationsis set to I_(mimo,max).

Step B⋅2 (iterative detection and the number of iterations k): When thenumber of iterations is k, λ_(k,na) and λ_(k,nb) are represented byEquations (31) to (34) from Equations (11), (13) to (15), (16), and(17). At this point, (X, Y)=(a, b), (b, a) is obtained.

In the iterative APP decoding:

$\begin{matrix}\lbrack {{Mathematical}\mspace{14mu} {formula}\mspace{14mu} 31} \rbrack & \; \\{\lambda_{k,n_{X}} = {{L_{{k - 1},\Omega_{{iX},{jX}}^{X}}( u_{\Omega_{{iX},{jX}}^{X}} )} + {\ln \frac{\sum_{U_{k,n_{X},{+ 1}}}{\exp \{ {{{- \frac{1}{2\sigma^{2}}}{\begin{matrix}{{y( i_{X} )} -} \\{{H_{22}( i_{X} )}{s( {u( i_{X} )} )}}\end{matrix}}^{2}} + {\rho ( u_{\Omega_{{iX},{jX}}^{X}} )}} \}}}{\sum_{U_{k,n_{X},{- 1}}}{\exp \{ {{{- \frac{1}{2\sigma^{2}}}{\begin{matrix}{{y( i_{X} )} -} \\{{H_{22}( i_{X} )}{s( {u( i_{X} )} )}}\end{matrix}}^{2}} + {\rho ( u_{\Omega_{{iX},{jX}}^{X}} )}} \}}}}}} & {{Equation}\mspace{14mu} (31)} \\\lbrack {{Mathematical}\mspace{14mu} {formula}\mspace{14mu} 32} \rbrack & \; \\{{\rho ( u_{\Omega_{{iX},{jX}}^{X}} )} = {{\sum\limits_{\underset{\gamma \neq {jX}}{\gamma = 1}}^{h}\; {{\frac{L_{{k - 1},\Omega_{{iX},\gamma}^{X}}( u_{\Omega_{{iX},\gamma}^{X}} )}{2}}( {{u_{\Omega_{{iX},\gamma}^{X}}{{sign}( {L_{{k - 1},\Omega_{{iX},\gamma}^{X}}( u_{\Omega_{{iX},\gamma}^{X}} )} )}} - 1} )}} + {\sum\limits_{\gamma = 1}^{h}\; {{\frac{L_{{k - 1},\Omega_{{iX},\gamma}^{Y}}( u_{\Omega_{{iX},\gamma}^{Y}} )}{2}}( {{u_{\Omega_{{iX},\gamma}^{Y}}{{sign}( {L_{{k - 1},\Omega_{{iX},\gamma}^{Y}}( u_{\Omega_{{iX},\gamma}^{Y}} )} )}} - 1} )}}}} & ( {{Equation}\mspace{14mu} (32)} \end{matrix}$

In iterative Max-log APP decoding:

$\begin{matrix}{\mspace{79mu} \lbrack {{Mathematical}\mspace{14mu} {formula}\mspace{14mu} 33} \rbrack} & \; \\{\lambda_{k,n_{X}} = {{L_{{k - 1},\Omega_{{iX},{jX}}^{X}}( u_{\Omega_{{iX},{jX}}^{X}} )} + {\max\limits_{U_{k,n_{X},{+ 1}}}\{ {\Psi ( {{u( i_{X} )},{y( i_{X} )},{\rho ( u_{\Omega_{{iX},{jX}}^{X}} )}} )} \}} - {\max\limits_{U_{k,n_{X},{- 1}}}\{ {\Psi ( {{u( i_{X} )},{y( i_{X} )},{\rho ( u_{\Omega_{{iX},{jX}}^{X}} )}} )} \}}}} & {{Equation}\mspace{14mu} (33)} \\{\mspace{79mu} \lbrack {{Mathematical}\mspace{14mu} {formula}\mspace{14mu} 34} \rbrack} & \; \\{{\Psi ( {{u( i_{X} )},{y( i_{X} )},{\rho ( u_{\Omega_{{iX},{jX}}^{X}} )}} )} = {{{- \frac{1}{2\sigma^{2}}}{{{y( i_{X} )} - {{H_{22}( i_{X} )}{s( {u( i_{X} )} )}}}}^{2}} + {\rho ( u_{\Omega_{{iX},{jX}}^{X}} )}}} & {{Equation}\mspace{14mu} (34)}\end{matrix}$

Step B⋅3 (counting of the number of iterations and codeword estimation):

If I_(mimo)<I_(mimo,max), I_(mimo) is incremented, and the processingreturns to Step B⋅2. Letting I_(mimo)=I_(mimo,max) leads to theestimated codeword using Equation (35).

$\begin{matrix}\lbrack {{Mathematical}\mspace{14mu} {formula}\mspace{14mu} 35} \rbrack & \; \\{{\hat{u}}_{n_{X}} = \{ \begin{matrix}1 & {L_{l_{mimo},n_{X}} \geq 0} \\{- 1} & {L_{l_{mimo},n_{X}} < 0}\end{matrix} } & {{Equation}\mspace{14mu} (35)}\end{matrix}$

Where X=a, b.

FIG. 5 illustrates a configuration example of transmission device of thefirst exemplary embodiment. Encoder 502A receives information (data)501A and frame structure signal 513 as input, performs the errorcorrection coding such as the convolutional coding, the LDPC coding, andthe turbo coding according to frame structure signal 513, and outputsencoded data 503A. Frame structure signal 513 includes information suchas an error correction scheme used in the error correction coding of thedata, a coding rate, a block length, and the like. Encoder 502A uses theerror correction scheme indicated by frame structure signal 513.Additionally, the error correction scheme may be switched.

Interleaver 504A receives encoded data 503A and frame structure signal513 as input, performs interleaving, namely, rearrangement of the order,and outputs interleaved data 505A. (The interleaving method may beswitched based on frame structure signal 513.)

Mapping unit 506A receives interleaved data 505A and the frame structuresignal 513 as input, performs modulation such as QPSK (Quadrature PhaseShift Keying), 16QAM (16 Quadrature Amplitude Modulation), and 64QAM (64Quadrature Amplitude Modulation), and outputs baseband signal 507A. (Themodulation scheme may be switched based on frame structure signal 513.)The modulation scheme is not limited to the QPSK, 16QAM, and 64QAM, butnon-uniform mapping may be performed. That is, plural signal points mayexist in an I-Q plane having in-phase component I and quadraturecomponent Q.

FIG. 7 illustrates an example of a mapping method on the I-Q planehaving in-phase component I and quadrature component Q. In-phasecomponent I and quadrature component Q form the baseband signal in theQPSK modulation. For example, as illustrated in FIG. 7A, I=1.0 and Q=1.0are output for the input data “00”. Similarly, I=−1.0 and Q=1.0 areoutput for the input data “01”. FIG. 7B is an example of a mappingmethod on the I-Q plane for the QPSK modulation different from that inFIG. 7A. The mapping method in FIG. 7B differs from the mapping methodin FIG. 7A in that the signal point in FIG. 7A is rotated about anorigin to obtain the signal point in FIG. 7B. NPLs 6 and 7 describe themethod for rotating the constellation, and Cyclic Q Delay described inNPLs 6 and 7 may also be applied.

FIG. 8 illustrates a signal point disposition in the I-Q plane for the16QAM as another example except for FIG. 7. FIG. 8A illustrates anexample corresponding to FIG. 7A, and FIG. 8B illustrates an examplecorresponding to FIG. 7B.

Encoder 502B receives information (data) 501B and frame structure signal513 as input and, performs the error correction coding such as theconvolutional coding, the LDPC coding, and the turbo coding according tothe frame structure signal 513, and outputs encoded data 503B. Framestructure signal 513 includes information such as the error correctionscheme used, the coding rate, and the block length. The error correctionscheme indicated by frame structure signal 513 is used. Additionally,the error correction scheme may be switched.

Interleaver 504B receives encoded data 503B and frame structure signal513 as input, performs the interleaving, namely, the rearrangement ofthe order, and outputs interleaved data 505B. (The interleaving methodmay be switched based on frame structure signal 513.) The modulationscheme is not limited to the QPSK, 16QAM, and 64QAM, but non-uniformmapping may be performed. That is, plural signal points may exist in theI-Q plane.

Mapping unit 506B receives interleaved data 505B and frame structuresignal 513 as input, performs the modulation such as QPSK (QuadraturePhase Shift Keying), 16QAM (16 Quadrature Amplitude Modulation), and64QAM (64 Quadrature Amplitude Modulation), and outputs baseband signal507B. (The modulation scheme may be switched based on frame structuresignal 513.)

Encoder 502C receives information (data) 501C and frame structure signal513 as input and, performs the error correction coding such as theconvolutional coding, the LDPC coding, and the turbo coding according tothe frame structure signal 513, and outputs encoded data 503C. Framestructure signal 513 includes information such as the error correctionscheme used, the coding rate, and the block length. The error correctionscheme indicated by frame structure signal 513 is used. Additionally,the error correction scheme may be switched.

Interleaver 504C receives encoded data 503C and frame structure signal513 as input, performs the interleaving, namely, the rearrangement ofthe order, and outputs interleaved data 505C. (The interleaving methodmay be switched based on frame structure signal 513.) The modulationscheme is not limited to the QPSK, 16QAM, and 64QAM, but non-uniformmapping may be performed. That is, plural signal points may exist in theI-Q plane.

Mapping unit 506C receives interleaved data 505C and frame structuresignal 513 as input, performs the modulation such as QPSK (QuadraturePhase Shift Keying), 16QAM (16 Quadrature Amplitude Modulation), and64QAM (64 Quadrature Amplitude Modulation), and outputs baseband signal507C. (The modulation scheme may be switched based on frame structuresignal 513.)

Signal processing method information generator 514 receives framestructure signal 513 as input, and outputs information 515 on a signalprocessing method based on frame structure signal 513. Information 515on the signal processing method includes information designating whichone of precoding matrices is fixedly used and information on a phasechanging pattern changing a phase.

Weighting unit 508A receives baseband signals 507A, 507B, and 507C andinformation 515 on the signal processing method as input, performsweighting on baseband signal 507A, baseband signal 507B, and basebandsignal 507C based on information 515 on the signal processing method,and outputs weighted signal 516A. The weighting method is described indetail later.

Phase changing unit 517A receives weighted signal 516A and information515 on the signal processing method as input, and regularly changes andoutputs the phase of signal 516A. The term “regularly change” means thatthe phase is changed according to a predetermined phase changing patternin a predetermined period (for example, every n symbol (n is an integerof 1 or more), every predetermined time, or every predeterminedfrequency). The detailed phase changing pattern is described later. (Thephase change need not be performed.)

Wireless unit 510A receives post-phase change signal 509A as input,performs pieces of processing such as quadrature modulation, bandlimiting, frequency conversion, and amplification, and outputstransmission signal 511A. Transmission signal 511A is output as a radiowave from antenna 512A.

Weighting unit 508B receives baseband signal 507A, baseband signal 507B,baseband signal 507C, and information 515 on the signal processingmethod as input, performs the weighting on baseband signal 507A,baseband signal 507B, and baseband signal 507C based on information 515on the signal processing method, and outputs weighted signal 512B. Theweighting method is described in detail later.

Phase changing unit 517B receives weighted signal 516B and information515 on the signal processing method as input, and regularly changes andoutputs the phase of signal 516B. The term “regularly change” means thatthe phase is changed according to a predetermined phase changing patternin a predetermined period (for example, every n symbol (n is an integerof 1 or more) or every predetermined time). The detailed phase changingpattern is described later. (The phase change need not be performed.)

Wireless unit 510B receives post-phase change signal 509B as input,performs pieces of processing such as the quadrature modulation, theband limiting, the frequency conversion, and the amplification, andoutputs transmission signal 511B. Transmission signal 511B is output asa radio wave from antenna 512B.

Weighting unit 508C receives baseband signal 507A, baseband signal 507B,baseband signal 507C, and information 515 on the signal processingmethod as input, performs the weighting on baseband signal 507A,baseband signal 507B, and baseband signal 507C based on information 515on the signal processing method, and outputs weighted signal 512C. Theweighting method is described in detail later.

Phase changing unit 517C receives weighted signal 516C and information515 on the signal processing method as input, and regularly changes andoutputs the phase of signal 516C. The term “regularly change” means thatthe phase is changed according to a predetermined phase changing patternin a predetermined period (for example, every n symbol (n is an integerof 1 or more) or every predetermined time). The detailed phase changingpattern is described later. (The phase change need not be performed.)

Wireless unit 510C receives post-phase change signal 509C as input,performs pieces of processing such as the quadrature modulation, theband limiting, the frequency conversion, and the amplification, andoutputs transmission signal 511C. Transmission signal 511C is output asa radio wave from antenna 512C.

FIG. 9 illustrates configurations of the weighting unit (508A, 508B, and508C) and the phase changing unit (517A, 517B, and 517C). An areasurrounded by a dotted line in FIG. 9 constitutes the weighting unit,and a subsequent stage of the weighting unit constitutes the phasechanging unit. Weighting units 508A, 508B, and 508C in FIG. 5 arecollectively illustrated as the weighting unit in FIG. 9. Phase changingunits 517A, 517B, and 517C in FIG. 5 are collectively illustrated as thephase changing unit in FIG. 9.

Baseband signal 507A is multiplied by w₁₁ to generate w₁₁×s₁(t),baseband signal 507A is multiplied by w₂₁ to generate w₂₁×s₁(t), andbaseband signal 507A is multiplied by w₃₁ to generate w₃₁×s₁(t).

Similarly, baseband signal 507B is multiplied by w₁₂ to generatew₁₂×s₂(t), baseband signal 507B is multiplied by w₂₂ to generatew₂₂×s₂(t), and baseband signal 507B is multiplied by w₃₂ to generatew₃₂×s₂(t).

Similarly, baseband signal 507C is multiplied by w₁₃ to generatew₁₃×s₃(t), baseband signal 507C is multiplied by w₂₃ to generatew₂₃×s₃(t), and baseband signal 507C is multiplied by w₃₃ to generatew₃₃×s₃(t).

At this point, as can be seen from the above description, s₁(t), s₂(t),and s₃(t) constitute the baseband signal (post-mapping baseband signal)of the modulation scheme such as the BPSK (Binary Phase Shift Keying),the QPSK, the 8PSK (8 Phase Shift Keying), the 16QAM, the 32QAM (32Quadrature Amplitude Modulation), the 64QAM, the 256QAM, and the 16APSK(16 Amplitude Phase Shift Keying).

For example, it is assumed that the weighting unit performs theweighting using the fixed precoding matrix. At this point, the precodingmatrix is expressed by Equation (36).

$\begin{matrix}\lbrack {{Mathematical}\mspace{14mu} {formula}\mspace{14mu} 36} \rbrack & \; \\{\begin{pmatrix}w_{11} & w_{12} & w_{13} \\w_{21} & w_{22} & w_{23} \\w_{31} & w_{32} & w_{33}\end{pmatrix} = \begin{pmatrix}a_{11} & a_{12} & a_{13} \\a_{21} & a_{22} & a_{23} \\a_{31} & a_{32} & a_{33}\end{pmatrix}} & {{Equation}\mspace{14mu} (36)}\end{matrix}$

Where a₁₁ is a complex number (may be a real number), a₁₂ is a complexnumber (may be a real number), a₁₃ is a complex number (may be a realnumber), a₂₁ is a complex number (may be a real number), a₂₂ is acomplex number (may be a real number), a₂₃ is a complex number (may be areal number), a₃₁ is a complex number (may be a real number), a₃₂ is acomplex number (may be a real number), and a₃₃ is a complex number (maybe a real number). Accordingly, a_(xy)=A_(xy)e^(jδxy) is obtained.(Where j is an imaginary unit, A_(xy) is a real number of 0 or more, andb_(xy) is an argument. x may be one of values 1, 2, and 3 and y may beone of values 1, 2, and 3.)

All a₁₁, a₁₂, and a₁₃ do not become 0 (zero), all a₂₁, a₂₂, and a₂₃ donot become 0 (zero), and all a₃₁, a₃₂, and a₃₃ do not become 0 (zero).All a₁₁, a₂₁, and a₃₁ do not become 0 (zero), all a₁₂, a₂₂, and a₃₂ donot become 0 (zero), and all a₁₃, a₂₃, and a₃₃ do not become 0 (zero).

Accordingly, in FIG. 9, Equation (37) holds when the weighted(post-precoding) signals are set to z₁′(t) (corresponding to 516A inFIG. 5), z₂′(t) (corresponding to 516B in FIG. 5), and z₃′(t)(corresponding to 516C in FIG. 5).

$\begin{matrix}\lbrack {{Mathematical}\mspace{14mu} {formula}\mspace{14mu} 37} \rbrack & \; \\\begin{matrix}{\begin{pmatrix}{z_{1}^{\prime}(t)} \\{z_{2}^{\prime}(t)} \\{z_{3}^{\prime}(t)}\end{pmatrix} = {\begin{pmatrix}w_{11} & w_{12} & w_{13} \\w_{21} & w_{22} & w_{23} \\w_{31} & w_{32} & w_{33}\end{pmatrix}\begin{pmatrix}{S_{1}(t)} \\{S_{2}(t)} \\{S_{3}(t)}\end{pmatrix}}} \\{= {\begin{pmatrix}a_{11} & a_{12} & a_{13} \\a_{21} & a_{22} & a_{23} \\a_{31} & a_{32} & a_{33}\end{pmatrix}\begin{pmatrix}{S_{1}(t)} \\{S_{2}(t)} \\{S_{3}(t)}\end{pmatrix}}}\end{matrix} & {{Equation}\mspace{14mu} (37)}\end{matrix}$

For example, the precoding matrix may be switched by the modulationscheme (or a set of modulation schemes (in FIG. 5, a set of threemodulation schemes)), the error correction coding scheme (for example,the error correction code used, or a code length (block length) of anerror correction code, and a coding rate of the error correction code).

In the above example, the fixed precoding matrix is used as theprecoding matrix by way of example. Alternatively, for example, theprecoding matrix may be switched by time. At this point, the precodingmatrix is expressed by Equation (38).

$\begin{matrix}\lbrack {{Mathematical}\mspace{14mu} {formula}\mspace{14mu} 38} \rbrack & \; \\{\begin{pmatrix}w_{11} & w_{12} & w_{13} \\w_{21} & w_{22} & w_{23} \\w_{31} & w_{32} & w_{33}\end{pmatrix} = \begin{pmatrix}{a_{11}(t)} & {a_{12}(t)} & {a_{13}(t)} \\{a_{21}(t)} & {a_{22}(t)} & {a_{23}(t)} \\{a_{31}(t)} & {a_{32}(t)} & {a_{33}(t)}\end{pmatrix}} & {{Equation}\mspace{14mu} (38)}\end{matrix}$

Where a₁₁(t) is a complex number (may be a real number), a₁₂(t) is acomplex number (may be a real number), a₁₃(t) is a complex number (maybe a real number), a₂₁(t) is a complex number (may be a real number),a₂₂(t) is a complex number (may be a real number), a₂₃(t) is a complexnumber (may be a real number), a₃₁(t) is a complex number (may be a realnumber), a₃₂(t) is a complex number (may be a real number), and a₃₃(t)is a complex number (may be a real number). Accordingly,a_(xy)(t)=A_(xy)(t)e^(jδxy)(t) is obtained. (Where j is an imaginaryunit, A_(xy)(t) is a real number of 0 or more, and δ_(xy)(t) is anargument. x may be one of values 1, 2, and 3 and y may be one of values1, 2, and 3.)

All a₁₁(t), a₁₂(t), and a₁₃(t) do not become 0 (zero), all a₂₁(t),a₂₂(t), and a₂₃(t) do not become 0 (zero), and all a₃₁(t), a₃₂(t), anda₃₃(t) do not become 0 (zero). All a₁₁(t), a₂₁(t), and a₃₁(t) do notbecome 0 (zero), all a₁₂(t), a₂₂(t), and a₃₂(t) do not become 0 (zero),and all a₁₃(t), a₂₃(t), and a₃₃(t) do not become 0 (zero).

Although the function of time t is used in Equation (38), a function offrequency (carrier) f or a function of both time t and frequency(carrier) f may be used. (The precoding matrix of Equation (38) is notlimited to these functions.)

As illustrated in FIG. 9, weighted (post-precoding) signal z₁′(t)(corresponding to 516A in FIG. 5) is subjected to the phase change toobtain post-phase change signal z₁(t) (corresponding to 509A in FIG. 5).At this point, assuming that y₁(t) is a phase change value, post-phasechange signal z₁(t) (corresponding to 509A in FIG. 5) is expressed byEquation (39).

[Mathematical formula 39]

z ₁(t)=y ₁(t)×z ₁′(t)  Equation (39)

Where y₁(t) is expressed as B₁×e^(jθ1(t)) or e^(jθ1(t)). It is assumedthat B₁ is a real number of 0 or more, and that θ₁(t) is an argument andis the function of time t. However, θ₁ is not limited to the function oftime t. For example, the function of frequency (carrier) f or thefunction of both time t and frequency (carrier) f may be used. (θ₁ isnot limited to these functions.)

y₁(t) is regularly changed. The term “regularly change” means that thephase is changed according to a predetermined phase changing pattern ina predetermined period (for example, every n symbol (n is an integer of1 or more) or every predetermined time). The detailed phase changingpattern is described later. (The phase change need not be performed.)

As illustrated in FIG. 9, weighted (post-precoding) signal z₂′(t)(corresponding to 516B in FIG. 5) is subjected to the phase change toobtain post-phase change signal z₂(t) (corresponding to 509B in FIG. 5).At this point, assuming that y₂(t) is a phase change value, post-phasechange signal z₂(t) (corresponding to 509B in FIG. 5) is expressed byEquation (40).

[Mathematical formula 40]

z ₂(t)=y ₂(t)×z ₂′(t)  Equation (40)

Where y₂(t) is expressed as B₂×e^(jθ2(t)) or e^(jθ2(t)). It is assumedthat B₂ is a real number of 0 or more, and that θ₂(t) is an argument andis the function of time t. However, θ₂ is not limited to the function oftime t. For example, the function of frequency (carrier) f or thefunction of both time t and frequency (carrier) f may be used. (θ₂ isnot limited to these functions.)

y₂(t) is regularly changed. The term “regularly change” means that thephase is changed according to a predetermined phase changing pattern ina predetermined period (for example, every n symbol (n is an integer of1 or more) or every predetermined time). The detailed phase changingpattern is described later. (The phase change need not be performed.)

As illustrated in FIG. 9, weighted (post-precoding) signal z₃′(t)(corresponding to 516C in FIG. 5) is subjected to the phase change toobtain post-phase change signal z₃(t) (corresponding to 509C in FIG. 5).At this point, assuming that y₃(t) is a phase changing value, post-phasechange signal z₃(t) (corresponding to 509C in FIG. 5) is expressed byEquation (41).

[Mathematical formula 41]

z ₃(t)=y ₃(t)×z ₃′(t)  Equation (41)

Where y₃(t) is expressed as B₃×e^(jθ3(t)) or e^(jθ3(t)). It is assumedthat B₃ is a real number of 0 or more, and that θ₃(t) is an argument andis the function of time t. However, θ₃ is not limited to the function oftime t. For example, the function of frequency (carrier) f or thefunction of both time t and frequency (carrier) f may be used. (θ₃ isnot limited to these functions.)

y₃(t) is regularly changed. The term “regularly change” means that thephase is changed according to a predetermined phase changing pattern ina predetermined period (for example, every n symbol (n is an integer of1 or more) or every predetermined time). The detailed phase changingpattern is described later. (The phase change need not be performed.)

FIG. 6 illustrates a configuration example of a transmission devicedifferent from that in FIG. 5. In FIG. 6, a point different from that inFIG. 5 will be described below.

Encoder 602 receives information (data) 601 and frame structure signal513 as input and, performs the error correction coding according toframe structure signal 513, and outputs encoded data 603.

Distributor 604 receives encoded data 603 as input, distributes data603, and outputs pieces of data 605A, 605B, and 605C. One encoder isillustrated in FIG. 6, but is not limited to one. Alternatively, thepresent disclosure may similarly be embodied when the distributordivides the encoded data generated by each of the m (where m is aninteger of 1 or more) encoders into pieces of data of three systems andoutputs the divided data.

FIG. 10 illustrates an example of a frame structure in a time axis ofthe transmission device of the first exemplary embodiment. Symbol 1000_1posts the reception device of the transmission method. For example,symbol 1000_1 transmits information such as the error correction schemeused to transmit a data symbol, the coding rate, and the modulationscheme used to transmit the data symbol.

Symbol 1001_1 estimates a channel fluctuation of modulated signal z₁(t)(where t is time) transmitted by the transmission device. Symbol 1002_1is a data symbol transmitted as symbol number u (on the time axis) bymodulated signal z₁(t), and symbol 1003_1 is a data symbol transmittedas symbol number u+1 by modulated signal z₁(t).

Symbol 1001_2 estimates a channel fluctuation of modulated signal z₂(t)(where t is time) transmitted by the transmission device. Symbol 1002_2is a data symbol transmitted as symbol number u by modulated signalz₂(t), and symbol 1003_2 is a data symbol transmitted as symbol numberu+1 by modulated signal z₂(t).

Symbol 1001_3 estimates a channel fluctuation of modulated signal z₃(t)(where t is time) transmitted by the transmission device. Symbol 1002_3is a data symbol transmitted as symbol number u by modulated signalz₃(t), and symbol 1003_3 is a data symbol transmitted as symbol numberu+1 by modulated signal z₃(t).

At this point, in the symbol of z₁(t), the symbol of z₂(t), and thesymbol of z₃(t), the symbol of the identical clock time (identical time)is transmitted from the transmit antenna at the identical (common)frequency.

A relationships between modulated signals z₁(t), z₂(t), and z₃(t)transmitted by the transmission device and received signals r₁(t),r₂(t), and r₃(t) received by the reception device will be describedbelow.

In FIG. 11, reference marks 1101#1, 1101#2, and 1101#3 designate thetransmit antennas of the transmission device, and reference marks1102#1, 1102#2, and 1102#3 designate the receive antennas of thereception device. The transmission device transmits the signalcorresponding to modulated signal z₁(t) from transmit antenna 1101#1,transmits the signal corresponding to modulated signal z₂(t) fromtransmit antenna 1101#2, and transmits the signal corresponding tomodulated signal z₃(t) from transmit antenna 1101#3. In this case, it isassumed that modulated signals z₁(t), z₂(t), and z₃(t) occupy theidentical (common) frequency (band).

Assuming that the channel fluctuations of the transmit antennas of thetransmission device and the receive antennas of the reception device areset to h₁₁(t), h₁₂(t), h₁₃(t), h₂₁(t), h₂₂(t), h₂₃(t), h₃₁(t), h₃₂(t),and h₃₃(t), that r₁(t) is the signal received by receive antenna 1102#1of reception device, that r₂(t) is the signal received by receiveantenna 1102#2 of reception device, and that r₃(t) is the signalreceived by receive antenna 1102#3 of reception device, Equation (42)holds.

$\begin{matrix}\lbrack {{Mathematical}\mspace{14mu} {formula}\mspace{14mu} 42} \rbrack & \; \\{\begin{pmatrix}{r_{1}(t)} \\{r_{2}(t)} \\{r_{3}(t)}\end{pmatrix} = {\begin{pmatrix}{h_{11}(t)} & {h_{12}(t)} & {h_{13}(t)} \\{h_{21}(t)} & {h_{22}(t)} & {h_{23}(t)} \\{h_{31}(t)} & {h_{32}(t)} & {h_{33}(t)}\end{pmatrix}\begin{pmatrix}{z_{1}(t)} \\{z_{2}(t)} \\{z_{3}(t)}\end{pmatrix}}} & {{Equation}\mspace{14mu} (42)}\end{matrix}$

FIG. 12A illustrates an example of the weighting unit (precoding method)and phase changing unit of the first exemplary embodiment. Weightingunit 1200 is one in which weighting units 508A, 508B, and 508C in FIG. 5are integrated.

FIG. 12B illustrates an example of the frame structure of the firstexemplary embodiment. Streams s₁(t), s₂(t), and s₃(t) correspond tobaseband signals 507A, 507B, and 507C in FIG. 5, namely, constitute thein-phase I component and quadrature Q component of the baseband signalaccording to the mapping of the modulation scheme such as the QPSK, the16QAM, and the 64QAM.

As indicated by the frame structure in FIG. 12B, stream s₁(t) indicatess₁(u) of symbol number u, s₁(u+1) of symbol number u+1, . . . .Similarly, the stream s₂(t) indicates s₂(u) of symbol number u, s₂(u+1)of symbol number u+1, . . . . Similarly, the stream s₃(t) indicatess₃(u) of symbol number u, s₃(u+1) of symbol number u+1, . . . .

Weighting unit 1200 receives baseband signals 507A (s₁(t)), 507B(s₂(t)), and 507C (s₃(t)) in FIG. 5 and information 515 on the signalprocessing method as input, performs the weighting according toinformation 515 on the signal processing method, and outputs weightedsignals 516A (z₁′(t)), 516B (z₂′(t)), and 516C (z₃′(t)) in FIG. 5.

Phase changing unit 517A changes the phase of weighted signal516A(z₁′(t)), and outputs post-phase change signal 509A(z₁(t)).

Phase changing unit 517B changes the phase of weighted signal516B(z₂′(t)), and outputs post-phase change signal 509B(z₂(t)).

Phase changing unit 517C changes the phase of weighted signal516C(z₃′(t)), and outputs post-phase change signal 509C(z₃(t)).

Assuming that (w₁₁,w₁₂,w₁₃) is vector W₁ of a first row in fixedprecoding matrix F, that (s₁(t),s₂(t),s₃(t))^(T) is S(t), and that y₁(t)is a phase changing equation of the phase changing unit, z₁(t) isexpressed by Equation (43).

[Mathematical formula 43]

z ₁(t)=y ₁(t)W ₁ S(t)  Equation (43)

It is also assumed that A^(T) is a transpose of matrix (or vector) A.

Assuming that (w₂₁,w₂₂,w₂₃) is vector W₂ of a second row in fixedprecoding matrix F and that y₂(t) is the phase changing equation of thephase changing unit, z₂(t) is expressed by Equation (44).

[Mathematical formula 44]

z ₂(t)=y ₂(t)W ₂ S(t)  Equation (44)

Assuming that (w₃₁,w₃₂,w₃₃) is vector W₃ of a third row in fixedprecoding matrix F and that y₃(t) is the phase changing equation of thephase changing unit, z₃(t) is expressed by Equation (45).

[Mathematical formula 45]

z ₃(t)=y ₃(t)W ₃ S(t)  Equation (45)

The phase changing method is described later.

FIG. 13 illustrates a configuration example of the transmission deviceof the first exemplary embodiment. Wireless unit 1303_X receivesreceived signal 1302_X received by antenna 1301_X as input, performspieces of processing such as the frequency conversion and the quadraturedemodulation, and outputs baseband signal 1304_X.

Channel fluctuation estimator 1305 for modulated signals z₁, z₂, and z₃transmitted by the transmission device receives baseband signal 1304_Xas input, extracts channel estimating reference symbol 1201_1 in FIG.12B, estimates the value corresponding to h₁₁ of Equation (42), andoutputs channel estimation signal 1306_1.

Channel fluctuation estimator 1305 for modulated signals z₁, z₂, and z₃transmitted by the transmission device receives baseband signal 1304_Xas input, extracts channel estimating reference symbol 1201_2 in FIG.12B, estimates the value corresponding to h₁₂ of Equation (42), andoutputs channel estimation signal 1306_2.

Channel fluctuation estimator 1305 for modulated signals z₁, z₂, and z₃transmitted by the transmission device receives baseband signal 1304_Xas input, extracts channel estimating reference symbol 1201_3 in FIG.12B, estimates the value corresponding to h₁₃ of Equation (42), andoutputs channel estimation signal 1306_3.

Wireless unit 1303_Y receives received signal 1302_Y received by antenna1301_Y as input, performs pieces of processing such as the frequencyconversion and the quadrature demodulation, and outputs baseband signal1304_Y.

Channel fluctuation estimator 1307 for modulated signals z₁, z₂, and z₃transmitted by the transmission device receives baseband signal 1304_Yas input, extracts channel estimating reference symbol 1201_1 in FIG.12B, estimates the value corresponding to h₂₁ of Equation (42), andoutputs channel estimation signal 1306_1.

Channel fluctuation estimator 1307 for modulated signals z₁, z₂, and z₃transmitted by the transmission device receives baseband signal 1304_Yas input, extracts channel estimating reference symbol 1201_2 in FIG.12B, estimates the value corresponding to h₂₂ of Equation (42), andoutputs channel estimation signal 1306_2.

Channel fluctuation estimator 1307 for modulated signals z₁, z₂, and z₃transmitted by the transmission device receives baseband signal 1304_Yas input, extracts channel estimating reference symbol 1201_3 in FIG.12B, estimates the value corresponding to h₂₃ of Equation (42), andoutputs channel estimation signal 1306_3.

Wireless unit 1303_Z receives received signal 1302_Z received by antenna1301_Z as input, performs pieces of processing such as the frequencyconversion and the quadrature demodulation, and outputs baseband signal1304_Z.

Channel fluctuation estimator 1309 for modulated signals z₁, z₂, and z₃transmitted by the transmission device receives baseband signal 1304_Zas input, extracts channel estimating reference symbol 1201_1 in FIG.12B, estimates the value corresponding to h₃₁ of Equation (42), andoutputs channel estimation signal 1310_1.

Channel fluctuation estimator 1309 for modulated signals z₁, z₂, and z₃transmitted by the transmission device receives baseband signal 1304_Zas input, extracts channel estimating reference symbol 1201_2 in FIG.12B, estimates the value corresponding to h₃₂ of Equation (42), andoutputs channel estimation signal 1310_2.

Channel fluctuation estimator 1309 for modulated signals z₁, z₂, and z₃transmitted by the transmission device receives baseband signal 1304_Zas input, extracts channel estimating reference symbol 1201_3 in FIG.12B, estimates the value corresponding to h₃₃ of Equation (42), andoutputs channel estimation signal 1310_3.

Control information decoder 1311 receives baseband signals 1304_X,1304_Y, and 1304_Z as input, detects symbol 1000_1 to post thetransmission method in FIG. 10, and outputs signal 1312 related to theinformation on the transmission method posted by the transmissiondevice.

Signal processor 1313 receives baseband signals 1304_X, 1304_Y, and1304_Z, channel estimation signals 1306_1, 1306_2, 1306_3, 1306_1,1306_2, 1306_3, 1310_1, 1310_2, and 1310_3, and signal 1312 related tothe information on the transmission method posted by the transmissiondevice, performs ML (Maximum Likelihood) detection, performs (errorcorrection) decoding, and outputs received data 1314_1, and/or 1314_2,and/or 1314_3.

The operation of signal processor 1313 in FIG. 13 will be supplemented.For example, it is assumed that signal processor 1313 performs the MLD(Maximum Likelihood Detection) processing described in NPLs 8, 9, and10.

The transmission method of the first exemplary embodiment is a MIMOtransmission method, in which the signal phase is regularly changedtogether with the time while the precoding matrix is used.

Assuming that H(t) is the (channel) matrix in Equation (42), that F isthe precoding weight matrix, that Y(t) (at this point, Y(t) depends ont) is the matrix of the phase changing equation of the phase changingunit in FIG. 12A, that (r₁(t),r₂(t),r₃(t))^(T) is received vector R(t),and that (s₁(t),s₂(t),s₃(t))^(T) is stream vector S(t), Equation (46)holds.

$\begin{matrix}\lbrack {{Mathematical}\mspace{14mu} {formula}\mspace{14mu} 46} \rbrack & \; \\{{{R(t)} = {{H(t)} \times {Y(t)} \times F \times {S(t)}}}{Where}{{Y(t)} = \begin{pmatrix}y_{1}^{(t)} & 0 & 0 \\0 & {y_{2}(t)} & 0 \\0 & 0 & {y_{3}(t)}\end{pmatrix}}} & {{Equation}\mspace{11mu} (46)}\end{matrix}$

a noise component is not described in Equation (46).

At this point, the reception device can perform the MLD on receivedvector R(t) by obtaining H(t)×Y(t)×F.

The operation of the MLD will be described below. In the followingdescription, it is assumed that the modulation schemes of modulatedsignals (streams) s₁, s₂, and s₃ are the QPSK.

First, (2 ⁶=64) candidate signal points corresponding to baseband signal1304_X are obtained from channel estimation signals 1306_1, 1306_2, and1306_3. FIG. 14 illustrates the state at that time. In FIG. 14, a mark ●(black circle) indicates the candidate signal point in the I-Q plane,and the 64 candidate signal points exist because of three systems ofQPSK. Assuming that b0 and b1 are 2 bits transmitted using modulatedsignal s₁, that b2 and b3 are 2 bits transmitted using modulated signals₂, and that b4 and b5 are 2 bits transmitted using modulated signal s₃,the candidate signal points corresponding to (b0, b1, b2, b3, b4, b5)exist in FIG. 14.

A square Euclidean distance between received signal point 1401(corresponding to baseband signal 1304_X) and each of the candidatesignal points is obtained. Each square Euclidean distance is divided bynoise variance σ². Accordingly, E_(X)(b0, b1, b2, b3, b4, b5) isobtained by dividing the square Euclidean distance between each of thecandidate signal points corresponding to (b0, b1, b2, b3, b4, b5) andthe received signal point by the noise variance, namely,E_(X)(1,1,1,1,1,1) is obtained from E_(X)(0,0,0,0,0,0). The basebandsignals and modulated signals s₁, s₂, and s₃ are complex signals.

Similarly, (2⁶=64) candidate signal points corresponding to basebandsignal 1304_Y are obtained from channel estimation signals 1306_1,1306_2, and 1306_3. FIG. 14 illustrates the state at that time. In FIG.14, the mark ● (black circle) indicates the candidate signal point onthe I-Q plane, and the 64 candidate signal points exist because of threesystems of the QPSK. Assuming that b0 and b1 are 2 bits transmittedusing modulated signal s₁, that b2 and b3 are 2 bits transmitted usingmodulated signal s₂, and that b4 and b5 are 2 bits transmitted usingmodulated signal s₃, the candidate signal points corresponding to (b0,b1, b2, b3, b4, b5) exist in FIG. 14. (However, the state in FIG. 14 isillustrated only by way of example.)

The square Euclidean distance between received signal point 1401(corresponding to baseband signal 1304_Y) and each of the candidatesignal points is obtained. Each square Euclidean distance is divided bynoise variance σ². Accordingly, E_(Y)(b0, b1, b2, b3, b4, b5) isobtained by dividing the square Euclidean distance between each of thecandidate signal points corresponding to (b0, b1, b2, b3, b4, b5) andthe received signal point by the noise variance, namely,E_(Y)(1,1,1,1,1,1) is obtained from E_(Y)(0,0,0,0,0,0). The basebandsignals and modulated signals s₁, s₂, and s₃ are complex signals.

Similarly, (2⁶=64) candidate signal points corresponding to basebandsignal 1304_Z are obtained from channel estimation signals 1310_1,1310_2, and 1310_3. FIG. 14 illustrates the state at that time. In FIG.14, the mark ● (black circle) indicates the candidate signal point onthe I-Q plane, and the 64 candidate signal points exist because of threesystems of the QPSK. Assuming that b0 and b1 are 2 bits transmittedusing modulated signal s₁, that b2 and b3 are 2 bits transmitted usingmodulated signal s₂, and that b4 and b5 are 2 bits transmitted usingmodulated signal s₃, the candidate signal points corresponding to (b0,b1, b2, b3, b4, b5) exist in FIG. 14. (However, the state in FIG. 14 isillustrated only by way of example.)

The square Euclidean distance between received signal point 1401(corresponding to baseband signal 1304_Z) and each of the candidatesignal points is obtained. Each square Euclidean distance is divided bynoise variance σ². Accordingly, E_(Z)(b0, b1, b2, b3, b4, b5) isobtained by dividing the square Euclidean distance between each of thecandidate signal points corresponding to (b0, b1, b2, b3, b4, b5) andthe received signal point by the noise variance, namely,E_(Z)(1,1,1,1,1,1) is obtained from E_(Z)(0,0,0,0,0,0). The basebandsignals and modulated signals s₁, s₂, and s₃ are complex signals.

E_(X)(b0, b1, b2, b3, b4, b5)+E_(Y)(b0, b1, b2, b3, b4, b5)+E_(Z)(b0,b1, b2, b3, b4, b5)=E(b0, b1, b2, b3, b4, b5) is obtained.

The value for ((b0,b1,b2,b3,b4,b5)=(0,0,0,0,0,0) constitutesE_(X)(0,0,0,0,0,0)+E_(Y)(0,0,0,0,0,0)+E_(Z)(0,0,0,0,0,0)=E(0,0,0,0,0,0),

the value for (b0,b1,b2,b3,b4,b5)=(0,0,0,0,0,1) constitutesE_(X)(0,0,0,0,0,1)+E_(Y)(0,0,0,0,0,1)+E_(Z)(0,0,0,0,0,1)=E(0,0,0,0,0,1),. . .the value for (b0,b1,b2,b3,b4,b5)=(1,1,1,1,1,1) constitutesE_(X)(1,1,1,1,1,1)+E_(Y)(1,1,1,1,1,1)+E_(Z)(1,1,1,1,1,1)=E(1,1,1,1,1,1)

For example, the logarithmic likelihood ratio of each bit is obtainedfrom E(b0,b1,b2,b3,b4,b5), the logarithmic likelihood ratios arerearranged (interleaved), the error correction decoding is performedusing the rearranged logarithmic likelihood ratio, and received data1314_1, and/or 1314_2, and/or 1314_3 is output.

The degradation of the data reception quality in the present disclosurewill be described below.

For convenience of explanation, it is assumed that baseband signal(post-mapping signal) s₃(t) does not exist. That is, baseband signals(post-mapping signals) s₁(t) and s₂(t) exist.

At this point, it is considered that the reception device in FIG. 13performs the reception. As described above, it is assumed that themodulation scheme of s₁(t) is the QPSK scheme, and that bits b0 and b1are transmitted. It is also assumed that the modulation scheme of s₂(t)is the QPSK scheme, and that bits b2 and b3 are transmitted.

FIG. 15 illustrates an example (the state of the candidate signal point)of the reception state of the I-Q plane in signal processor 1313 of FIG.13. In FIG. 15, the mark ● (black circle) indicates the candidate signalpoint on the IQ plane, b0 and b1 are transmitted using s₁(t), and b2 andb3 are transmitted using s₂(t). Therefore, ideally the 16 candidatesignal points exist as illustrated in FIG. 15. (The candidate signalpoints in which (b0,b1,b2,b3) corresponds to (0,0,0,0) to (1,1,1,1)exist.)

FIG. 16 illustrates an example (the state of the candidate signal point)of the reception state of the I-Q plane in signal processor 1313 of FIG.13. In FIG. 16, the mark ● (black circle) indicates the candidate signalpoint on the IQ plane.

Candidate signal point 1602 is the candidate signal point in which(b0,b1,b2,b3) corresponds to (0,0,0,0).

Candidate signal point 1603 is the candidate signal point in which(b0,b1,b2,b3) corresponds to (0,0,0,1) and (0,1,0,0).

Candidate signal point 1604 is the candidate signal point in which(b0,b1,b2,b3) corresponds to (0,1,0,1).

Candidate signal point 1605 is the candidate signal point in which(b0,b1,b2,b3) corresponds to (1,1,0,1) and (0,1,1,1).

Candidate signal point 1606 is the candidate signal point in which(b0,b1,b2,b3) corresponds to (1,1,1,1).

Candidate signal point 1607 is the candidate signal point in which(b0,b1,b2,b3) corresponds to (1,1,1,0) and (1,0,1,1).

Candidate signal point 1608 is the candidate signal point in which(b0,b1,b2,b3) corresponds to (1,0,1,0).

Candidate signal point 1609 is the candidate signal point in which(b0,b1,b2,b3) corresponds to (1,0,0,0) and (0,0,1,0).

Candidate signal point 1610 is the candidate signal point in which(b0,b1,b2,b3) corresponds to (0,0,1,1), (0,1,1,0,), (1,1,0,0), and(1,0,0,1).

In FIG. 16, the number of candidate signal points decreases comparedwith the ideal state in FIG. 15. When the reception is performed in thestate of FIG. 16, the data reception quality degrades in the receptiondevice. Particularly, in an environment where a direct wave is dominant,a propagation environment is steady because of a strong influence of thedirect wave, which results in a phenomenon in which the low datareception quality continues for a long time. In FIG. 16, by way ofexample, the candidate signal points overlap each other. For example,similarly the decreases of the minimum Euclidean distances of the 16candidate signal points lead to the degradation of the data receptionquality. (Particularly, there is a high possibility of generating thedegradation of the data reception quality in the environment where thedirect wave is dominant.)

The phenomenon in which the candidate signal points overlap each otheris also generated in the case that the three baseband signals, namely,s₁(t), s₂(t), and s₃(t) exist. A method for improving the data receptionquality in the case that “particularly, in the environment where thedirect wave is dominant, the propagation environment is steady becauseof the strong influence of the direct wave, which results in thephenomenon in which the low data reception quality continues for a longtime” will be described below.

FIG. 17 illustrates specific examples of the phase change values inphase changing units 517A, 517B, and 517C of the transmission device inFIGS. 5 and 6. As described above, it is assumed that y₁(t) is the phasechange value of phase changing unit 517A, that y₂(t) is the phase changevalue of phase changing unit 517B, and that y₃(t) is the phase changevalue of phase changing unit 517C. In FIG. 17, t is the time (althoughy₁(t), y₂(t), and y₃(t) are the function of the time in this case, thephase change value may be the function of the frequency or the frequencyand time as described above), “0” means the 0 radian, “a” means the aradian, “b” means the b radian, where 0≤a<2π, 0<b<2π, a≠0, b≠0, and a≠b.

As illustrated in FIG. 17, it is assumed that

-   -   at clock time t=0, y₁(0)=0 (radian), y₂(0)=0 (radian), y₃(0)=0        (radian)    -   at clock time t=1, y₁(1)=0 (radian), y₂(1)=a (radian), y₃(1)=0        (radian)    -   at clock time t=2, y₁(2)=0 (radian), y₂(2)=b (radian), y₃(2)=0        (radian)    -   at clock time t=3, y₁(3)=0 (radian), y₂(3)=0 (radian), y₃(3)=0        (radian)    -   at clock time t=4, y₁(4)=0 (radian), y₂(4)=a (radian), y₃(4)=0        (radian)    -   at clock time t=5, y₁(5)=0 (radian), y₂(5)=b (radian), y₃(5)=0        (radian)    -   . . . .

In FIG. 17, it is assumed that there are three periods with respect tothe phase change. Accordingly,

-   -   at clock time t=3k, y₁(3k)=0 (radian), y₂(3k)=0 (radian),        y₃(3k)=0 (radian)    -   at clock time t=3k+1, y₁(3k+1)=0 (radian), y₂(3k+1)=a (radian),        y₃(3k+1)=0 (radian)    -   at clock time t=3k+2, y₁(3k+2)=0 (radian), y₂(3k+2)=b (radian),        y₃(3k+2)=0 (radian)        are obtained. For example, k is an integer of 0 or more.

The degradation of the data reception quality in performing the phasechange in FIG. 17 will be described below.

For example, it is considered that the reception device in FIG. 13receives the modulated signal transmitted from antenna 512B with the lowreception field strength when the reception device in FIG. 13 receivesthe modulated signal transmitted by the transmission device in FIGS. 5and 6. In the following description, as described above, it is assumedthat the modulation schemes of modulated signals (streams) s₁, s₂, ands₃ are the QPSK. Accordingly, in the case that the candidate signalpoints do not overlap each other in performing the MLD, the 64 candidatesignal points emerge on the I-Q plane.

As described above, it is considered that the reception device in FIG.13 receives the modulated signal transmitted from antenna 512B with thelow reception field strength. It is considered that the minimumEuclidean distance is short at the 64 candidate signal points to degradethe data reception quality when the MLD is performed in the environmentin which the direct wave is dominant. It is considered that the casephase change in FIG. 17 is performed under the environment.

In this case, the signal having an influence on the reception state ofthe reception device in FIG. 13 becomes the modulated signal transmittedfrom antenna 512A of the transmission device in FIGS. 5 and 6 and themodulated signal transmitted from antenna 512C.

In the case that the phase change in FIG. 17 is performed, the phasechange is not performed on the modulated signal transmitted from antenna512A of the transmission device in FIGS. 5 and 6, and the phase changeis not performed on the modulated signal transmitted from antenna 512Cof the transmission device in FIGS. 5 and 6. Accordingly, in FIG. 13,there is a high possibility that the state of the candidate signal pointon the I-Q plane is not largely changed with respect to time t. (Thereis a high possibility of slightly changing the minimum Euclideandistance of the candidate signal point.) Therefore, there is apossibility of retaining the state in the case that the data receptionquality degrades in the reception device of FIG. 13.

FIG. 18 illustrates an example of the phase changing method as a measurein the case that the data reception quality degrades in the receptiondevice of FIG. 13.

FIG. 18 illustrates specific examples of the phase change values inphase changing units 517A, 517B, and 517C of the transmission device inFIGS. 5 and 6. As described above, it is assumed that y₁(t) is the phasechange value of phase changing unit 517A, that y₂(t) is the phase changevalue of phase changing unit 517B, and that y₃(t) is the phase changevalue of phase changing unit 517C. In FIG. 17, t is the time (althoughy₁(t), y₂(t), and y₃(t) are the function of the time in this case, thephase change value may be the function of the frequency or the frequencyand time as described above), “0” means the 0 radian, “a” means the aradian, “b” means the b radian, where 0≤a<2π, 0≤b<2π, a≠0, b≠0, and a≠b.

As illustrated in FIG. 18, it is assumed that

-   -   at clock time t=0, y₁(0)=0 (radian), y₂(0)=0 (radian), y₃(0)=0        (radian)    -   at clock time t=1, y₁(1)=0 (radian), y₂(1)=a (radian), y₃(1)=0        (radian)    -   at clock time t=2, y₁(2)=0 (radian), y₂(2)=b (radian), y₃(2)=0        (radian)    -   at clock time t=3, y₁(3)=0 (radian), y₂(3)=0 (radian), y₃(3)=a        (radian)    -   at clock time t=4, y₁(4)=0 (radian), y₂(4)=0 (radian), y₃(4)=b        (radian)    -   at clock time t=5, y₁(5)=0 (radian), y₂(5)=a (radian), y₃(5)=a        (radian)    -   at clock time t=6, y₁(6)=0 (radian), y₂(6)=a (radian), y₃(6)=b        (radian)    -   at clock time t=7, y₁(7)=0 (radian), y₂(7)=b (radian), y₃(7)=a        (radian)    -   at clock time t=8, y₁(8)=0 (radian), y₂(8)=b (radian), y₃(8)=b        (radian)    -   . . . .

In FIG. 18, it is assumed that there are nine periods with respect tothe phase change. Accordingly,

-   -   at clock time t=9k, y₁(9k)=0 (radian), y₂(9k)=0 (radian),        y₃(9k)=0 (radian)    -   at clock time t=9k+1, y₁(9k+1)=0 (radian), y₂(9k+1)=a (radian),        y₃(9k+1)=0 (radian)    -   at clock time t=9k+2, y₁(9k+2)=0 (radian), y₂(9k+2)=b (radian),        y₃(9k+2)=0 (radian)    -   at clock time t=9k+3, y₁(9k+3)=0 (radian), y₂(9k+3)=0 (radian),        y₃(9k+3)=a (radian)    -   at clock time t=9k+4, y₁(9k+4)=0 (radian), y₂(9k+4)=0 (radian),        y₃(9k+4)=b (radian)    -   at clock time t=9k+5, y₁(9k+5)=0 (radian), y₂(9k+5)=a (radian),        y₃(9k+5)=a (radian)    -   at clock time t=9k+6, y₁(9k+6)=0 (radian), y₂(9k+6)=a (radian),        y₃(9k+6)=b (radian)    -   at clock time t=9k+7, y₁(9k+7)=0 (radian), y₂(9k+7)=b (radian),        y₃(9k+7)=a (radian)    -   at clock time t=9k+8, y₁(9k+8)=0 (radian), y₂(9k+8)=b (radian),        y₃(9k+8)=b (radian)        are obtained. For example, k is an integer of 0 or more.

An advantage of the phase change in FIG. 18 will be described below.

Similarly to the description in FIG. 17, for example, it is consideredthat the reception device in FIG. 13 receives the modulated signaltransmitted from antenna 512B with the low reception field strength whenthe reception device in FIG. 13 receives the modulated signaltransmitted by the transmission device in FIGS. 5 and 6. In thefollowing description, as described above, it is assumed that themodulation schemes of modulated signals (streams) s₁, s₂, and s₃ are theQPSK. Accordingly, in the case that the candidate signal points do notoverlap each other in performing the MLD, the 64 candidate signal pointsemerge on the I-Q plane.

As described above, it is considered that the reception device in FIG.13 receives the modulated signal transmitted from antenna 512B with thelow reception field strength. It is considered that the minimumEuclidean distance is short at the 64 candidate signal points to degradethe data reception quality when the MLD is performed in the environmentin which the direct wave is dominant. It is considered that the casephase change in FIG. 18 is performed under the environment.

In this case, the signal having an influence on the reception state ofthe reception device in FIG. 13 becomes the modulated signal transmittedfrom antenna 512A and the modulated signal transmitted from antenna 512Cof the transmission device in FIGS. 5 and 6.

In the case that the phase change in FIG. 18 is performed, the phasechange is not performed on the modulated signal transmitted from antenna512A of the transmission device in FIGS. 5 and 6 at times t=0, t=1, andt=2, and the phase change is not performed on the modulated signaltransmitted from antenna 512C of the transmission device in FIGS. 5 and6 at times t=0, t=1, and t=2. Accordingly, in FIG. 13, there is a highpossibility that the state of the candidate signal point on the I-Qplane is not largely changed at times t=0, t=1, and t=2. (There is ahigh possibility of slightly changing the minimum Euclidean distance ofthe candidate signal point.)

At times t=3 to t=8, because the phase except for 0 (zero) radian isprovided in the modulated signal transmitted from antenna 512C of thetransmission device in FIGS. 5 and 6, there is a possibility ofimproving the state of the candidate signal point on the I-Q plane (theminimum Euclidean distance of the candidate signal point increases).

When compared with the phase change in FIG. 17, the time for which thecandidate signal point is in good state (the candidate signal point hasthe large minimum Euclidean distance) increases to obtain anadvantageous effect that the reception quality is improved by applyingthe error correction code.

It is considered that the reception device in FIG. 13 receives themodulated signal transmitted from antenna 512C with the low receptionfield strength. It is considered that the minimum Euclidean distance isshort at the 64 candidate signal points to degrade the data receptionquality when the MLD is performed in the environment in which the directwave is dominant. It is considered that the case phase change in FIG. 18is performed under the environment.

In this case, the signal having an influence on the reception state ofthe reception device in FIG. 13 becomes the modulated signal transmittedfrom antenna 512A and the modulated signal transmitted from antenna 512Bof the transmission device in FIGS. 5 and 6.

In the case that the phase change in FIG. 18 is performed, the phasechange is not performed on the modulated signal transmitted from antenna512A of the transmission device in FIGS. 5 and 6 at times t=0, t=3, andt=4, and the phase change is not performed on the modulated signaltransmitted from antenna 512B of the transmission device in FIGS. 5 and6 at times t=0, t=3, and t=4. Accordingly, in FIG. 13, there is a highpossibility that the state of the candidate signal point on the I-Qplane is not largely changed at times t=0, t=3, and t=4. (There is ahigh possibility of slightly changing the minimum Euclidean distance ofthe candidate signal point.)

However, at times t=1, t=2, t=5, t=6, t=7, and t=8, because the phaseexcept for 0 (zero) radian is provided in the modulated signaltransmitted from antenna 512B of the transmission device in FIGS. 5 and6, there is a possibility of improving the state of the candidate signalpoint on the I-Q plane (the minimum Euclidean distance of the candidatesignal point increases).

When compared with the phase change in FIG. 17, the time for which thecandidate signal point is in good state (the candidate signal point hasthe large minimum Euclidean distance) increases to obtain anadvantageous effect that the reception quality is improved by applyingthe error correction code.

It is considered that the reception device in FIG. 13 receives themodulated signal transmitted from antenna 512A with the low receptionfield strength. It is considered that the minimum Euclidean distance isshort at the 64 candidate signal points to degrade the data receptionquality when the MLD is performed in the environment in which the directwave is dominant. It is considered that the case phase change in FIG. 18is performed under the environment.

In this case, the signal having an influence on the reception state ofthe reception device in FIG. 13 becomes the modulated signal transmittedfrom antenna 512B and the modulated signal transmitted from antenna 512Cof the transmission device in FIGS. 5 and 6.

A relative phase relationship between the modulated signal transmittedfrom antenna 512B of the transmission device in FIGS. 5 and 6 and themodulated signal transmitted from antenna 512C of the transmissiondevice in FIGS. 5 and 6 does not change at times t=0, t=5, and t=8 inthe case that the phase change in FIG. 18 is performed. (A phasedifference between the modulated signal transmitted from antenna 512B ofthe transmission device in FIGS. 5 and 6 and the modulated signaltransmitted from antenna 512C of the transmission device in FIGS. 5 and6 becomes an identical value at times t=0, t=5, and t=8.) Accordingly,in FIG. 13, there is a high possibility that the state of the candidatesignal point on the I-Q plane is not largely changed at times t=0, t=5,and t=8. (There is a high possibility of slightly changing the minimumEuclidean distance of the candidate signal point.) (The state of thecandidate signal point does not change in the case that the relativephase relationship does not change.)

However, the relative phase relationship between the modulated signaltransmitted from antenna 512B of the transmission device in FIGS. 5 and6 and the modulated signal transmitted from antenna 512C of thetransmission device in FIGS. 5 and 6 changes at times t=1, t=2, t=3,t=4, t=6, and t=7, the plurality of phases are provided in the modulatedsignal transmitted from antenna 512B of the transmission device in FIGS.5 and 6, and the plurality of phases are provided in the modulatedsignal transmitted from antenna 512C of the transmission device in FIGS.5 and 6. Therefore, there is a possibility of improving the state of thecandidate signal point on the I-Q plane (the minimum Euclidean distanceof the candidate signal point increases) at times t=1, t=2, t=3, t=4,t=6, and t 7.

When compared with the phase change in FIG. 17, the time for which thecandidate signal point is in good state (the candidate signal point hasthe large minimum Euclidean distance) increases to obtain anadvantageous effect that the reception quality is improved by applyingthe error correction code.

Thus, even if any one of the states of transmit antennas 512A, 512B, and512C in FIGS. 5 and 6 degrades, an advantageous effect that apossibility of degrading the data reception quality is lowered can beobtained.

The example of the phase change and the advantageous effect inperforming the phase change in FIG. 18 are described above. Anotherexample of the phase changing method in which the similar advantageouseffect is obtained will be described below.

It is assumed that a₁ is a value that can be taken by phase change valuey₁(t) of phase changing unit 517A in FIGS. 5 and 6. In FIG. 18,y₁(t)=a₁=0 holds.

It is assumed that m (m is an integer of 2 or more) kinds of values canbe taken by phase change value y₂(t) of phase changing unit 517B inFIGS. 5 and 6, and b_(i) (radian) is the value that can be expressed byphase change value y₂(t) (i is an integer between 1 and m (inclusive),and 0≤b_(i)<2π). At this point, i and j are integers between 1 and m(inclusive), i≠j, and b_(i)≠b_(j) is satisfied for any i and j. In FIG.18, y₂(t)=b_(i)=0, a, b holds.

It is assumed that n (n is an integer of 2 or more) kinds of values canbe taken by phase change value y₃(t) of phase changing unit 517C inFIGS. 5 and 6, and c_(i) (radian) is the value that can be taken byphase change value y₃(t) (i is an integer between 1 and n (inclusive),and 0≤c_(i)<2π). At this point, i and j are integers between 1 and n(inclusive), i≠j, and c_(i)≠c_(j) is satisfied for any i and j. In FIG.18, y₃(t)=c_(l)=0, a, b holds.

Assuming that (a₁, b_(i), c_(j)) is a value taken by a set of (y₁(u),y₂(u), y₃(u)) in symbol number u (u is an integer of 0 or more), thefollowing conditions are satisfied.

(Condition 1)

It is assumed that i=β holds. (β is an integer between 1 and m(inclusive).) At this point, that y₁(u),y₂(u),y₃(u))=(a₁,b_(β),c_(j))holds ((y₁(u),y₂(u),y₃(u))=(a₁,b_(β),c_(j)) means y₁(u)=a₁, y₂(u)=b_(β),and y₃(u)=c_(j)). When i=β is satisfied in integer u of 0 or more, jtakes all the values of the integer between 1 and n (inclusive) inc_(j).

(Condition 2)

The condition that “j takes all the values of the integers between 0 andn (inclusive) in c_(j) when i=β is satisfied in integer u of 0 or more”is satisfied in β of all the integers between 1 and m (inclusive).

The advantageous effect can be obtained by satisfying (Condition 1) and(Condition 2) when the phase change is performed as illustrated in FIG.18. Although m×n is the minimum value of the period of the phase changesatisfying (Condition 1) and (Condition 2), the period of the phasechange may be greater than or equal to m×n. (In this case, the identicalset of phase changes is used at least twice, and the period of the phasechange is set under that condition.)

The phase changing method in the case that phase change value y₁(t) ofthe phase changing unit 517A in FIGS. 5 and 6 is set to a constant valueis described in the example of FIG. 18 and the above example. The phasechanging method in the case that phase change value y₁(t) of the phasechanging unit 517A in FIGS. 5 and 6 is changed according to the time(frequency) (frequency and time) will be described below.

It is assumed that p (p is an integer of 2 or more) kinds of values canbe taken by phase change value y₁(t) of phase changing unit 517A inFIGS. 5 and 6, and a_(i) (radian) is the value that can be taken byphase change value y₁(t) (i is an integer between 1 and p (inclusive),and 0≤a_(i)<2π). At this point, i and j are integers between 1 and p(inclusive), i≠j, and a_(i)≠a_(j) is satisfied for any i and j.

It is assumed that m (m is an integer of 2 or more) kinds of values canbe taken by phase change value y₂(t) of phase changing unit 517B inFIGS. 5 and 6, and b_(i) (radian) is the value that can be taken byphase change value y₂(t) (i is an integer between 1 and m (inclusive),and 0≤b_(i)<2π). At this point, i and j are integers between 1 and m(inclusive), i≠j, and b_(i)≠b_(j) is satisfied for any i and j.

It is assumed that n (n is an integer of 2 or more) kinds of values canbe taken by phase change value y₃(t) of phase changing unit 517C inFIGS. 5 and 6, and ci (radian) is the value that can be taken by phasechange value y₃(t) (i is an integer between 1 and n (inclusive), and0≤c_(i)<2π). At this point, i and j are integers between 1 and n(inclusive), i≠j, and c_(i)≠c_(j) is satisfied for any i and j.

Assuming that (a_(i), b_(j), c_(k)) is a value taken by the set of(y₁(u),y₂(u),y₃(u)) in symbol number u (u is an integer of 0 or more),the following conditions are satisfied.

(Condition 3)

It is assumed that i=β holds. (β is an integer between 1 and p(inclusive).) At this point, that(y₁(u),y₂(u),y₃(u))=(a_(β),b_(j),c_(k)) holds((y₁(u),y₂(u),y₃(u))=(a_(β),b_(j),c_(k)) means y₁(u)=a_(β), y₂(u)=b_(j),and y₃(u)=c_(k)). When i=β is satisfied in integer u of 0 or more, in(a_(β),b_(j),c_(k)), j is an integer between 0 and m (inclusive), k isan integer between 0 and n (inclusive), and a set (j,k) that can betaken by (j,k) exists.

(Condition 4)

A condition that, “when i=β is satisfied in integer u of 0 or more, in(a_(β),b_(j),c_(k)), j is an integer between 0 and m (inclusive), k isan integer between 0 and n (inclusive), and a set (j,k) that can betaken by (j,k) exists” is satisfied in β of all the integers between 1and p (inclusive).

The advantageous effect can be obtained by satisfying (Condition 3) and(Condition 4) when the phase change is performed as illustrated in FIG.18. Although p×m×n is the minimum value of the period of the phasechange satisfying (Condition 3) and (Condition 4), the period of thephase change may be greater than or equal to p×m×n. (In this case, theidentical set of phase changes is used at least twice, and the period ofthe phase change is set under that condition.)

The example in which H(t)×Y(t)×F is obtained to perform the MLD in thereception device is described above. Alternatively, the detection may beperformed using QR decomposition as described in NPL 9.

As described in NPL 11, based on H(t)×Y(t)×F, MMSE (Minimum Mean SquareError) and ZF (Zero Forcing) are linearly calculated to perform thedetection.

Additionally, in the first exemplary embodiment, the single carrierscheme is described by way of example. However, the present disclosureis not limited the single carrier scheme, but may be similarly embodiedfor multi-carrier transmission. Accordingly, for example, when a spreadspectrum communication scheme, an OFDM (Orthogonal Frequency-DivisionMultiplexing) scheme, SC-FDMA (Single Carrier Frequency DivisionMultiple Access) scheme, SC-OFDM (Single Carrier OrthogonalFrequency-Division Multiplexing) scheme, or a wavelet OFDM schemedescribed in NPL 12 is used, the present disclosure may be similarlyembodied. In the first exemplary embodiment, such a symbol other thanthe data symbol as a pilot symbols (a preamble, a unique word, and thelike) and a symbol transmitting control information may arbitrarily bearranged in the frame.

An example in the OFDM scheme is used will be described as an example ofa multi-carrier scheme.

FIGS. 19 and 20 illustrate a configuration of a transmission device whenthe OFDM scheme is used. In FIG. 19, the component operating similarlyto FIGS. 5 and 6 is designated by the identical reference mark.

OFDM scheme-related processor 1901A receives post-phase change signal509A as input, performs processing related to the OFDM scheme, andoutputs transmission signal 1902A. Similarly, OFDM scheme-relatedprocessor 1901B receives post-phase change signal 509B as input andoutputs transmission signal 1902B, and OFDM scheme-related processor1901C receives post-phase change signal 509C as input and outputstransmission signal 1902C.

FIG. 21 illustrates a configuration example subsequent to OFDMscheme-related processors 1901A, 1901B, and 1901C in FIGS. 19 and 20.Components 2101A to 2110A correspond to components 1901A to 512A inFIGS. 19 and 20, components 2101B to 2110B correspond to components1901B to 512B, and components 2101C to 2110C correspond to components1901C to 512C.

Serial-parallel converter 2102A performs the serial-parallel conversionon weighted signal 2101A (corresponding to weighted signal 509A in FIGS.19 and 20) and outputs parallel signal 2103A.

Rearranger 2104A receives parallel signal 2103A as input, performs therearrangement, and outputs rearranged signal 2105A. The rearrangement isdescribed in detail later.

Inverse fast Fourier transformer 2106A receives rearranged signal 2105Aas input, performs the inverse fast Fourier transform, and outputspost-inverse fast Fourier transform signal 2107A.

Wireless unit 2108A receives post-inverse fast Fourier transform signal2107A as input, performs the pieces of processing such as the frequencyconversion and the amplification, and outputs modulated signal 2109A.Modulated signal 2109A is output as a radio wave from antenna 2110A.

Serial-parallel converter 2102B performs serial-parallel conversion onweighted signal 2101B (corresponding to weighted signal 509B in FIGS. 19and 20) and outputs parallel signal 2103B.

Rearranger 2104B receives parallel signal 2103B as input, performs therearrangement, and outputs rearranged signal 2105B. The rearrangement isdescribed in detail later.

Inverse fast Fourier transformer 2106B receives the rearranged signal2105B as input, performs the inverse fast Fourier transform, and outputspost-inverse fast Fourier transform signal 2107B.

Wireless unit 2108B receives post-inverse fast Fourier transform signal2107B as input, performs the pieces of processing such as the frequencyconversion and the amplification, and outputs modulated signal 2109B.Modulated signal 2109B is output as a radio wave from antenna 2110B.

Serial-parallel converter 2102C performs the serial-parallel conversionon weighted signal 2101C (corresponding to weighted signal 509C in FIGS.19 and 20) and outputs parallel signal 2103C.

Rearranger 2104C receives parallel signal 2103C as input, performs therearrangement, and outputs rearranged signal 2105C. The rearrangement isdescribed in detail later.

Inverse fast Fourier transformer 2106C receives rearranged signal 2105Cas input, performs the inverse fast Fourier transform, and outputspost-inverse fast Fourier transform signal 2107C.

Wireless unit 2108C receives post-inverse fast Fourier transform signal2107C as input, performs the pieces of processing such as the frequencyconversion and the amplification, and outputs modulated signal 2109C.Modulated signal 2109C is output as a radio wave from antenna 2110C.

Because the transmission scheme in which the multi-carrier is used isnot adopted in the transmission device in FIGS. 5 and 6, the post-phasechange symbol is disposed in a time axis direction. When such themulti-carrier transmission method as the OFDM scheme in FIGS. 19 and 20is adopted, it is conceivable that, for each (sub) carrier, the symbolthat is subjected to the precoding and phase change is disposed in thetime axis direction as illustrated in FIGS. 5 and 6. For themulti-carrier transmission scheme, it is also conceivable that thesymbol is disposed in the frequency axis direction, or both thefrequency axis and time axis directions. This point will be describedbelow.

FIG. 22 illustrates an example of the symbol rearranging method on ahorizontal axis indicating the frequency and a vertical axis indicatingthe time in rearrangers 2104A, 2104B, and 2104C in FIG. 21. In FIG. 22,the frequency axis is constructed with (sub) carrier 0 to (sub) carrier9. Modulated signals z₁, z₂, and z₃ use the identical frequency band atthe same clock time (time). FIG. 22A illustrates a method forrearranging the symbol of modulated signal z₁, FIG. 22B illustrates themethod for rearranging the symbol of modulated signal z₂, and FIG. 22Cillustrates the method for rearranging the symbol of modulated signalz₃. Numbers #0, #1, #2, #3, . . . are sequentially assigned to thesymbol of weighted and post phase change signal 2101A input toserial-parallel converter 2102A.

At this point, as illustrated in FIG. 22A, symbols #0, #1, #2, #3, . . .are regularly disposed from carrier 0 such that symbols #0 to #9 aresequentially disposed at clock time $1, and such that symbols #10 to #19are sequentially disposed at clock time $2. Modulated signals z₁, z₂,and z₃ are complex signals.

Similarly, numbers #0, #1, #2, #3, . . . are assigned to the symbols ofweighted and post phase change signal 2101B which is input toserial-parallel converter 2102B.

At this point, as illustrated in FIG. 22B, symbols #0, #1, #2, #3, . . .are regularly disposed from carrier 0 such that symbols #0 to #9 aresequentially disposed at clock time $1, and such that symbols #10 to #19are sequentially disposed at clock time $2.

Similarly, numbers #0, #1, #2, #3, . . . are sequentially assigned tothe symbol of weighted and post phase change signal 2101C which is inputto serial-parallel converter 2102C.

At this point, as illustrated in FIG. 22C, symbols #0, #1, #2, #3, . . .are regularly disposed from carrier 0 such that symbols #0 to #9 aresequentially disposed at clock time $1, and such that symbols #10 to #19are sequentially disposed at clock time $2.

Thus, when such the multi-carrier transmission method as OFDM scheme isused, the symbols can be disposed in the frequency axis direction unlikethe single carrier transmission. The disposition of the symbols is notlimited to that in FIG. 22. Other examples will be described withreference to FIGS. 23 and 24.

FIG. 23 illustrates another example, which is different from FIG. 22, ofthe symbol rearranging method on the horizontal axis indicating thefrequency and the vertical axis indicating the time in rearrangers2104A, 2104B, and 2104C in FIG. 21. FIG. 23A illustrates the method forrearranging the symbol of modulated signal z₁, FIG. 23B illustrates themethod for rearranging the symbol of modulated signal z₂, and FIG. 23Cillustrates the method for rearranging the symbol of modulated signalz₃. The symbol rearranging method in FIG. 23 differs from the symbolrearranging method in FIG. 22 in the method for rearranging the symbolsof the modulated signals z₁, z₂, and z₃. In FIG. 23B, symbols #0 to #5are disposed in carriers 4 to 9, symbols #6 to #9 are disposed incarriers 0 to 3, and symbols #10 to #19 are disposed in each of thecarriers in the similar way. In FIG. 23C, symbols #0 to #5 are disposedin carriers 4 to 9, symbols #6 to #9 are disposed in carriers 0 to 3,and symbols #10 to #19 are disposed in each of the carriers in thesimilar way.

FIG. 24 illustrates another example, which is different from FIG. 22, ofthe symbol rearranging method on the horizontal axis indicating thefrequency and the vertical axis indicating the time in rearrangers2104A, 2104B, and 2104C in FIG. 21. FIG. 24A illustrates the method forrearranging the symbol of modulated signal z₁, FIG. 24B illustrates themethod for rearranging the symbol of modulated signal z₂, and FIG. 24Cillustrates the method for rearranging the symbol of modulated signalz₃. The symbol rearranging method in FIG. 24 differs from the symbolrearranging method in FIG. 22 in that the symbols are not sequentiallydisposed in FIG. 24 while the symbols are sequentially disposed in FIG.22. In FIG. 24, similarly to FIG. 23, the methods for rearranging thesymbols of the modulated signals z₁, z₂, and z₃ may differ from oneanother.

FIG. 25 illustrates another example, which is different from FIG. 22 toFIG. 24, of the symbol rearranging method on the horizontal axisindicating the frequency and the vertical axis indicating the time inrearrangers 2104A, 2104B, and 2104C in FIG. 21. FIG. 25A illustrates themethod for rearranging the symbol of modulated signal z₁, FIG. 25Billustrates the method for rearranging the symbol of modulated signalz₂, and FIG. 25C illustrates the method for rearranging the symbol ofmodulated signal z₃. The symbols are arranged in both the frequency axisand time axis directions in FIS. 25, while the symbols are arranged inthe frequency axis direction in FIGS. 22 to 24.

FIG. 26 illustrates another example, which is different from FIG. 25, ofthe symbol rearranging method on the horizontal axis indicating thefrequency and the vertical axis indicating the time in rearrangers2104A, 2104B, and 2104C in FIG. 21. FIG. 26A illustrates the method forrearranging the symbol of modulated signal z₁, FIG. 26B illustrates themethod for rearranging the symbol of modulated signal z₂, and FIG. 26Cillustrates the method for rearranging the symbol of modulated signalz₃. In FIG. 26, similarly to FIG. 25, the symbols are disposed on boththe frequency and time axes. The symbol rearranging method in FIG. 26differs from the symbol rearranging method in FIG. 25 in the followingpoint. That is, in FIG. 25, high priority is given to the frequency axisdirection and then the symbols are disposed on the time axis direction.On the other hand, in FIG. 26, high priority is given to the time axisdirection and then the symbols are disposed on the frequency axisdirection.

Although the symbol disposing methods are described in some drawings,the symbol disposing method is not limited to the above methods. Thesymbol may randomly be disposed on the time-frequency axis, or disposeaccording to a certain rule.

Accordingly, the first exemplary embodiment leads to the followingadvantageous effect. That is, there is a high possibility of improvingthe data reception quality, and particularly there is a high possibilityof largely improving the data reception quality in the LOS environmentin which the direct wave is dominant.

For example, the precoding matrix may be switched when the set ofmodulation schemes of the three streams is switched. The phase changingmethod may be switched when the set of modulation schemes of the threestreams is switched. The precoding matrix and the phase changing methodmay be switched when the set of modulation schemes of the three streamsis switched. (The precoding matrix and the phase changing need not beswitched even if the set of modulation schemes of the three streams isswitched).

For the interleaver, the data need not be rearranged.

Second Exemplary Embodiment

The transmission method, reception method, transmission device, andreception device in the case that the three streams are transmittedusing the three antennas are described in the first exemplaryembodiment.

A transmission method, a reception method, a transmission device, and areception device in the case that four streams that can obtain theadvantageous effect similar to that of the first exemplary embodimentare transmitted using four antennas will be described in a secondexemplary embodiment.

FIG. 27 illustrates a configuration example of the transmission deviceof the second exemplary embodiment. In FIG. 27, the component operatingsimilarly to FIG. 5 is designated by the identical reference mark. Thetransmission device in FIG. 27 differs from the transmission device inFIG. 5 in that fourth coded data exists. The operation of the componentassociated with the fourth coded data will be described below. (Theoperations of other component are similar to those in FIG. 5 of thefirst exemplary embodiment.)

Encoder 502D receives information (data) 501D and frame structure signal513 as input, performs the error correction coding such as theconvolutional coding, the LDPC coding, and the turbo coding according toframe structure signal 513, and outputs encoded data 503D. Framestructure signal 513 includes information such as an error correctionscheme used in the error correction coding of the data, a coding rate, ablock length, and the like. Encoder 502D uses the error correctionscheme indicated by frame structure signal 513. Additionally, the errorcorrection scheme may be switched.

Interleaver 504D receives encoded data 503D and frame structure signal513 as input, performs the interleaving, namely, the rearrangement, andoutputs interleaved data 505D. (The interleaving method may be switchedbased on frame structure signal 513.)

Mapping unit 506D receives interleaved data 505D and frame structuresignal 513 as input, performs the modulation such as QPSK (QuadraturePhase Shift Keying), 16QAM (16 Quadrature Amplitude Modulation), and64QAM (64 Quadrature Amplitude Modulation), and outputs baseband signal507D. (The modulation scheme may be switched based on frame structuresignal 513.) The modulation scheme is not limited to the QPSK, 16QAM,and 64QAM, but non-uniform mapping may be performed. That is, pluralsignal points may exist in the I-Q plane.

Weighting unit 508A receives baseband signals 507A, 507B, 507C, and 507Dand information 515 on the signal processing method as input, performsthe weighting on baseband signals 507A, 507B, 507C, and 507D based oninformation 515 on the signal processing method, and outputs weightedsignal 516A. The weighting method is described in detail later.

Weighting unit 508B receives baseband signals 507A, 507B, 507C, and 507Dand information 515 on the signal processing method as input, performsthe weighting on baseband signals 507A, 507B, 507C, and 507D based oninformation 515 on the signal processing method, and outputs weightedsignal 516B. The weighting method is described in detail later.

Weighting unit 508C receives baseband signals 507A, 507B, 507C, and 507Dand information 515 on the signal processing method as input, performsthe weighting on baseband signals 507A, 507B, 507C, and 507D based oninformation 515 on the signal processing method, and outputs weightedsignal 516C. The weighting method is described in detail later.

Weighting unit 508D receives baseband signals 507A, 507B, 507C, and 507Dand information 515 on the signal processing method as input, performsthe weighting on baseband signals 507A, 507B, 507C, and 507D based oninformation 515 on the signal processing method, and outputs weightedsignal 516D. The weighting method is described in detail later.

Phase changing unit 517D receives weighted signal 516D and information515 on the signal processing method as input, and regularly changes andoutputs the phase of signal 516D. The term “regularly change” means thatthe phase is changed according to a predetermined phase changing patternin a predetermined period (for example, every n symbol (n is an integerof 1 or more) or every predetermined time). The detailed phase changingpattern is described later. (The phase change need not be performed.)

FIG. 29 illustrates configurations of the weighting unit (508A, 508B,508C, and 508D) and the phase changing unit (517A, 517B, 517C, and517D). An area surrounded by a dotted line in FIG. 29 constitutes theweighting unit, and a subsequent stage of the weighting unit constitutesthe phase changing unit. Weighting units 508A, 508B, 508C, and 508D inFIG. 27 are collectively illustrated as the weighting unit in FIG. 29.Phase changing units 517A, 517B, 517C, and 517D in FIG. 27 arecollectively illustrated as the phase changing unit in FIG. 29.

Baseband signal 507A is multiplied by w₁₁ to generate w₁₁×s₁(t),baseband signal 507A is multiplied by w₂₁ to generate w₂₁×s₁(t),baseband signal 507A is multiplied by w₃₁ to generate w₃₁×s₁(t), andbaseband signal 507A is multiplied by w₄₁ to generate w₄₁×s₁(t).

Similarly, baseband signal 507B is multiplied by w₁₂ to generateW₁₂×s₂(t), baseband signal 507B is multiplied by w₂₂ to generatew₂₂×s₂(t), baseband signal 507B is multiplied by w₃₂ to generatew₃₂×s₂(t), and baseband signal 507B is multiplied by w₄₂ to generatew₄₂×s₂(t).

Similarly, baseband signal 507C is multiplied by w₁₃ to generatew₁₃×s₃(t), baseband signal 507C is multiplied by w₂₃ to generatew₂₃×s₃(t), baseband signal 507C is multiplied by w₃₃ to generatew₃₃×s₃(t), and baseband signal 507C is multiplied by w₄₃ to generatew₄₃×s₃(t).

Similarly, baseband signal 507D is multiplied by w₁₄ to generateW₁₄×s₄(t), baseband signal 507D is multiplied by w₂₄ to generatew₂₄×s₄(t), baseband signal 507D is multiplied by w₃₄ to generatew₃₄×s₄(t), and baseband signal 507D is multiplied by w₄₄ to generatew₄₄×s₄(t).

At this point, as can be seen from the above description, s₁(t), s₂(t),s₃(t), and s₄(t) constitute the baseband signal (post-mapping basebandsignal) of the modulation scheme such as the BPSK (Binary Phase ShiftKeying), the QPSK, the 8PSK (8 Phase Shift Keying), the 16QAM, the 32QAM(32 Quadrature Amplitude Modulation), the 64QAM, the 256QAM, and the16APSK (16 Amplitude Phase Shift Keying).

For example, it is assumed that the weighting unit performs theweighting using the fixed precoding matrix. At this point, the precodingmatrix is expressed by Equation (47).

$\begin{matrix}\lbrack {{Mathematical}\mspace{14mu} {formula}\mspace{14mu} 47} \rbrack & \; \\{\begin{pmatrix}w_{11} & w_{12} & w_{13} & w_{14} \\w_{21} & w_{22} & w_{23} & w_{24} \\w_{31} & w_{32} & w_{33} & w_{34} \\w_{41} & w_{42} & w_{43} & w_{44}\end{pmatrix} = \begin{pmatrix}a_{11} & a_{12} & a_{13} & a_{14} \\a_{21} & a_{22} & a_{23} & a_{24} \\a_{31} & a_{32} & a_{33} & a_{34} \\a_{41} & a_{42} & a_{43} & a_{44}\end{pmatrix}} & {{Equation}\mspace{14mu} (47)}\end{matrix}$

Where a₁₁ is a complex number (may be a real number), a₁₂ is a complexnumber (may be a real number), a₁₃ is a complex number (may be a realnumber), a₁₄ is a complex number (may be a real number), a₂₁ is acomplex number (may be a real number), a₂₂ is a complex number (may be areal number), a₂₃ is a complex number (may be a real number), a₂₄ is acomplex number (may be a real number), a₃₁ is a complex number (may be areal number), a₃₂ is a complex number (may be a real number), a₃₃ is acomplex number (may be a real number), a₃₄ is a complex number (may be areal number), a₄₁ is a complex number (may be a real number), a₄₂ is acomplex number (may be a real number), a₄₃ is a complex number (may be areal number), and a₄₄ is a complex number (may be a real number).Accordingly, a_(xy)=A_(xy)e^(jδxy) is obtained. (Where j is an imaginaryunit, A_(xy) is a real number of 0 or more, and δ_(xy) is an argument. xmay be one of values 1, 2, 3, and 4 and y may be one of values 1, 2, 3,and 4.)

All a₁₁, a₁₂, a₁₃, and a₁₄ do not become 0 (zero), all a₂₁, a₂₂, a₂₃,and a₂₄ do not become 0 (zero), all a₃₁, a₃₂, a₃₃, and a₃₄ do not become0 (zero), and all a₄₁, a₄₂, a₄₃, and a₄₄ do not become 0 (zero). Alla₁₁, a₂₁, a₃₁, and a₄₁ do not become 0 (zero), all a₁₂, a₂₂, a₃₂, anda₄₂ do not become 0 (zero), all a₁₃, a₂₃, a₃₃, and a₄₃ do not become 0(zero), and all a₁₄, a₂₄, a₃₄, and a₄₄ do not become 0 (zero).

Accordingly, in FIG. 27, Equation (48) holds when the weighted(post-precoding) signals are set to z₁′(t) (corresponding to 516A inFIG. 27), z₂′(t) (corresponding to 516B in FIG. 27), z₃′(t)(corresponding to 516C in FIG. 27), and z₄′(t) (corresponding to 516D inFIG. 27).

$\begin{matrix}\lbrack {{Mathematical}\mspace{14mu} {formula}\mspace{14mu} 48} \rbrack & \; \\\begin{matrix}{\begin{pmatrix}{z_{1}^{\prime}(t)} \\{z_{2}^{\prime}(t)} \\{z_{3}^{\prime}(t)} \\{z_{4}^{\prime}(t)}\end{pmatrix} = {\begin{pmatrix}w_{11} & w_{12} & w_{13} & w_{14} \\w_{21} & w_{22} & w_{23} & w_{24} \\w_{31} & w_{32} & w_{33} & w_{34} \\w_{41} & w_{42} & w_{43} & w_{44}\end{pmatrix}\begin{pmatrix}{S_{1}(t)} \\{S_{2}(t)} \\{S_{3}(t)} \\{S_{4}(t)}\end{pmatrix}}} \\{= {\begin{pmatrix}a_{11} & a_{12} & a_{13} & a_{14} \\a_{21} & a_{22} & a_{23} & a_{24} \\a_{31} & a_{32} & a_{33} & a_{34} \\a_{41} & a_{42} & a_{43} & a_{44}\end{pmatrix}\begin{pmatrix}{S_{1}(t)} \\{S_{2}(t)} \\{S_{3}(t)} \\{S_{4}(t)}\end{pmatrix}}}\end{matrix} & {{Equation}\mspace{14mu} (48)}\end{matrix}$

For example, the precoding matrix may be switched by the modulationscheme (or a set of modulation schemes (in FIG. 27, a set of fourmodulation schemes)), the error correction coding scheme (for example,the error correction code used, or a code length (block length) of anerror correction code, and a coding rate of the error correction code).

In the above example, the fixed precoding matrix is used as theprecoding matrix by way of example. Alternatively, for example, theprecoding matrix may be switched by time. At this point, the precodingmatrix is expressed by Equation (49).

$\begin{matrix}{\mspace{79mu} \lbrack {{Mathematical}\mspace{14mu} {formula}\mspace{14mu} 49} \rbrack} & \; \\{\begin{pmatrix}w_{11} & w_{12} & w_{13} & w_{14} \\w_{21} & w_{22} & w_{23} & w_{24} \\w_{31} & w_{32} & w_{33} & w_{34} \\w_{41} & w_{42} & w_{43} & w_{44}\end{pmatrix} = \begin{pmatrix}{a_{11}(t)} & {a_{12}(t)} & {a_{13}(t)} & {a_{14}(t)} \\{a_{21}(t)} & {a_{22}(t)} & {a_{23}(t)} & {a_{24}(t)} \\{a_{31}(t)} & {a_{32}(t)} & {a_{33}(t)} & {a_{34}(t)} \\{a_{41}(t)} & {a_{42}(t)} & {a_{43}(t)} & {a_{44}(t)}\end{pmatrix}} & {{Equation}\mspace{14mu} (49)}\end{matrix}$

Where a₁₁(t) is a complex number (may be a real number), a₁₂(t) is acomplex number (may be a real number), a₁₃(t) is a complex number (maybe a real number), a₁₄(t) is a complex number (may be a real number),a₂₁(t) is a complex number (may be a real number), a₂₂(t) is a complexnumber (may be a real number), a₂₃(t) is a complex number (may be a realnumber), a₂₄(t) is a complex number (may be a real number), a₃₁(t) is acomplex number (may be a real number), a₃₂(t) is a complex number (maybe a real number), a₃₃(t) is a complex number (may be a real number),a₃₄(t) is a complex number (may be a real number), a₄₁(t) is a complexnumber (may be a real number), a₄₂(t) is a complex number (may be a realnumber), a₄₃(t) is a complex number (may be a real number), and a₄₄(t)is a complex number (may be a real number). Accordingly,a_(xy)(t)=A_(xy)(t)e^(jδxy(t)) is obtained. (Where j is an imaginaryunit, A_(xy)(t) is a real number of 0 or more, and δ_(xy)(t) is anargument. x may be one of values 1, 2, 3, and 4 and y may be one ofvalues 1, 2, 3, and 4.)

All a₁₁(t), a₁₂(t), a₁₃(t), and a₁₄(t) do not become 0 (zero), alla₂₁(t), a₂₂(t), a₂₃(t), and a₂₄(t) do not become 0 (zero), all a₃₁(t),a₃₂(t), a₃₃(t), and a₃₄(t) do not become 0 (zero), and all a₄₁(t),a₄₂(t), a₄₃(t), and a₄₄(t) do not become 0 (zero). All a₁₁(t), a₂₁(t),a₃₁(t), and a₄₁(t) do not become 0 (zero), all a₁₂(t), a₂₂(t), a₃₂(t),and a₄₂(t) do not become 0 (zero), all a₁₃(t), a₂₃(t), a₃₃(t), anda₄₃(t) do not become 0 (zero), and all a₁₄(t), a₂₄(t), a₃₄(t), anda₄₄(t) do not become 0 (zero).

Although the function of time t is used in Equation (49), a function offrequency (carrier) f or a function of both time t and frequency(carrier) f may be used. (The precoding matrix of Equation (49) is notlimited to these functions.)

As illustrated in FIG. 29, weighted (post-precoding) signal z₁′(t)(corresponding to 516A in FIG. 27) is subjected to the phase change toobtain post-phase change signal (corresponding to 509A in FIG. 27)z₁(t). At this point, assuming that y₁(t) is a phase changing value,post-phase change signal (corresponding to 509A in FIG. 27) z₁(t) isexpressed by Equation (50).

[Mathematical formula 50]

z ₁(t)=y ₁(t)×z ₁′(t)  Equation (50)

Where y₁(t) is expressed as B₁×e^(jθ1(t)) or e^(jθ1(t)). It is assumedthat B₁ is a real number of 0 or more, and that 61(t) is an argument andis the function of time t. However, θ₁ is not limited to the function oftime t. For example, the function of frequency (carrier) f or thefunction of both time t and frequency (carrier) f may be used. (θ₁ isnot limited to these functions.)

y₁(t) is regularly changed. The term “regularly change” means that thephase is changed according to a predetermined phase changing pattern ina predetermined period (for example, every n symbol (n is an integer of1 or more) or every predetermined time). The detailed phase changingpattern is described later. (The phase change need not be performed.)

As illustrated in FIG. 29, weighted (post-precoding) signal z₂′(t)(corresponding to 516B in FIG. 27) is subjected to the phase change toobtain post-phase change signal (corresponding to 509B in FIG. 27)z₂(t). At this point, assuming that y₂(t) is a phase changing value,post-phase change signal (corresponding to 509B in FIG. 27) z₂(t) isexpressed by Equation (51).

[Mathematical formula 51]

z ₂(t)=y ₂(t)×z ₂′(t)  Equation (51)

Where y₂(t) is expressed as B₂×e^(jθ2(t)) or e^(jθ2(t)). It is assumedthat B₂ is a real number of 0 or more, and that θ₂(t) is an argument andis the function of time t. However, θ₂ is not limited to the function oftime t. For example, the function of frequency (carrier) f or thefunction of both time t and frequency (carrier) f may be used. (θ₂ isnot limited to these functions.)

y₂(t) is regularly changed. The term “regularly change” means that thephase is changed according to a predetermined phase changing pattern ina predetermined period (for example, every n symbol (n is an integer of1 or more) or every predetermined time). The detailed phase changingpattern is described later. (The phase change need not be performed.)

As illustrated in FIG. 29, weighted (post-precoding) signal z₃′(t)(corresponding to 516C in FIG. 27) is subjected to the phase change toobtain post-phase change signal (corresponding to 509C in FIG. 27)z₃(t). At this point, assuming that y₃(t) is a phase changing value,post-phase change signal (corresponding to 509C in FIG. 27) z₃(t) isexpressed by Equation (52).

[Mathematical formula 52]

z ₃(t)=y ₃(t)×z ³′(t)  Equation (52)

Where y₃(t) is expressed as B₃×e^(jθ3(t)) or e^(jθ3(t)). It is assumedthat B₃ is a real number of 0 or more, and that θ₃(t) is an argument andis the function of time t. However, θ₃ is not limited to the function oftime t. For example, the function of frequency (carrier) f or thefunction of both time t and frequency (carrier) f may be used. (θ₃ isnot limited to these functions.)

y₃(t) is regularly changed. The term “regularly change” means that thephase is changed according to a predetermined phase changing pattern ina predetermined period (for example, every n symbol (n is an integer of1 or more) or every predetermined time). The detailed phase changingpattern is described later. (The phase change need not be performed.)

As illustrated in FIG. 29, weighted (post-precoding) signal z₄′(t)(corresponding to 516D in FIG. 27) is subjected to the phase change toobtain post-phase change signal (corresponding to 509D in FIG. 27)z₄(t). At this point, assuming that y₄(t) is a phase changing value,post-phase change signal (corresponding to 509D in FIG. 27) z₄(t) isexpressed by Equation (53).

[Mathematical formula 53]

z ₄(t)=y ₄(t)×z ₄′(t)  Equation (53)

Where y₄(t) is expressed as B₄×e^(jθ4(t)) or e^(jθ4(t)). It is assumedthat B₄ is a real number of 0 or more, and that θ₄(t) is an argument andis the function of time t. However, θ₄ is not limited to the function oftime t. For example, the function of frequency (carrier) f or thefunction of both time t and frequency (carrier) f may be used. (θ₄ isnot limited to these functions.)

y₄(t) is regularly changed. The term “regularly change” means that thephase is changed according to a predetermined phase changing pattern ina predetermined period (for example, every n symbol (n is an integer of1 or more) or every predetermined time). The detailed phase changingpattern is described later. (The phase change need not be performed.)

FIG. 28 illustrates a configuration example of a transmission devicedifferent from that in FIG. 27. In FIG. 28, a point different from thatin FIG. 27 will be described below.

Encoder 602 receives information (data) 601 and frame structure signal513 as input and, performs the error correction coding according toframe structure signal 513, and outputs encoded data 603.

Distributor 604 receives encoded data 603 as input, distributes data603, and outputs pieces of data 605A, 605B, 605C, and 605D.

For the coded data of 64800 bits, 64800 bits are divided into four toobtain group A of 16200 bits, group B of 16200 bits, group C of 16200bits, and group D of 16200 bits. A method for allocating group A of16200 bits to data 605A, allocating group B of 16200 bits to data 605B,allocating group C of 16200 bits to data 605C, and allocating group D of16200 bits to data 605D is considered. (64800 bits may be divided in anyway. Therefore, the numbers of bits of group A, group B, group C, andgroup D may different from one another.) (The same holds true for FIG. 6of the first exemplary embodiment.)

One encoder is illustrated in FIG. 28. Alternatively, the presentdisclosure may similarly be embodied when the distributor divides theencoded data generated by each of the m (where m is an integer of 1 ormore) encoders into pieces of data of four systems and outputs thedivided data.

FIG. 30 illustrates an example of a frame structure in a time axis ofthe transmission device of the second exemplary embodiment. Symbol1000_1 posts the reception device of the transmission method. Forexample, symbol 1000_1 transmits information such as the errorcorrection scheme used to transmit a data symbol, the coding rate, andthe modulation scheme used to transmit the data symbol.

Symbol 1001_1 estimates a channel fluctuation of modulated signal z₁(t)(where t is time) transmitted by the transmission device. Symbol 1002_1is a data symbol transmitted as symbol number u (on the time axis) bymodulated signal z₁(t), and symbol 1003_1 is a data symbol transmittedas symbol number u+1 by modulated signal z₁(t).

Symbol 1001_2 estimates a channel fluctuation of modulated signal z₂(t)(where t is time) transmitted by the transmission device. Symbol 1002_2is a data symbol transmitted as symbol number u by modulated signalz₂(t), and symbol 1003_2 is a data symbol transmitted as symbol numberu+1 by modulated signal z₂(t).

Symbol 1001_3 estimates a channel fluctuation of modulated signal z₃(t)(where t is time) transmitted by the transmission device. Symbol 1002_3is a data symbol transmitted as symbol number u by modulated signalz₃(t), and symbol 1003_3 is a data symbol transmitted as symbol numberu+1 by modulated signal z₃(t).

Symbol 1001_4 estimates a channel fluctuation of modulated signal z₄(t)(where t is time) transmitted by the transmission device. Symbol 1002_4is a data symbol transmitted as symbol number u by modulated signalz₄(t), and symbol 1003_4 is a data symbol transmitted as symbol numberu+1 by modulated signal z₄(t).

At this point, in the symbol of z₁(t), the symbol of z₂(t), the symbolof z₃(t), and the symbol of z₄(t), the symbol of the identical clocktime (identical time) is transmitted from the transmit antenna at theidentical (common) frequency.

A relationships between modulated signals z₁(t), z₂(t), z₃(t), and z₄(t)transmitted by the transmission device and received signals r₁(t),r₂(t), r₃(t), and r₄(t) received by the reception device will bedescribed below.

In FIG. 31, reference marks 1101#1, 1101#2, 1101#3, and 1101#4 designatethe transmit antennas of the transmission device, and reference marks1102#1, 1102#2, 1102#3, and 1102#4 designate the receive antennas of thereception device. The transmission device transmits the signalcorresponding to modulated signal z₁(t) from transmit antenna 1101#1,transmits the signal corresponding to modulated signal z₂(t) fromtransmit antenna 1101#2, transmits the signal corresponding to modulatedsignal z₃(t) from transmit antenna 1101#3, and transmits the signalcorresponding to modulated signal z₄(t) from transmit antenna 1101#4. Inthis case, it is assumed that modulated signals z₁(t), z₂(t), and z₃(t),and z₄(t) occupy the identical (common) frequency (band).

The channel fluctuations of each transmit antenna of the transmissiondevice and each antenna of the reception device are set to h₁₁(t),h₁₂(t), h₁₃(t), h₁₄(t), h₂₁(t), h₂₂(t), h₂₃(t), h₂₄(t), h₃₁(t), h₃₂(t),h₃₃(t), h₃₄(t), h₄₁(t), h₄₂(t), h₄₃(t), and h₄₄(t).

Assuming that r₁(t) is the signal received by receive antenna 1102#1 ofreception device, that r₂(t) is the signal received by receive antenna1102#2 of reception device, that r₃(t) is the signal received by receiveantenna 1102#3 of reception device, and that r₄(t) is the signalreceived by receive antenna 1102#4 of reception device, Equation (54)holds.

$\begin{matrix}\lbrack {{Mathematical}\mspace{14mu} {formula}\mspace{14mu} 54} \rbrack & \; \\{\begin{pmatrix}{r_{1}(t)} \\{r_{2}(t)} \\{r_{3}(t)} \\{r_{4}(t)}\end{pmatrix} = {\begin{pmatrix}{h_{11}(t)} & {h_{12}(t)} & {h_{13}(t)} & {h_{14}(t)} \\{h_{21}(t)} & {h_{22}(t)} & {h_{23}(t)} & {h_{24}(t)} \\{h_{31}(t)} & {h_{32}(t)} & {h_{33}(t)} & {h_{34}(t)} \\{h_{41}(t)} & {h_{42}(t)} & {h_{43}(t)} & {h_{44}(t)}\end{pmatrix}\begin{pmatrix}{z_{1}(t)} \\{z_{2}(t)} \\{z_{3}(t)} \\{z_{4}(t)}\end{pmatrix}}} & {{Equation}\mspace{14mu} (54)}\end{matrix}$

FIG. 32A illustrates an example of the weighting unit (precoding method)and phase changing unit of the second exemplary embodiment. Weightingunit 1200 is one in which weighting units 508A, 508B, 508C, and 508D inFIG. 27 are integrated.

FIG. 32B illustrates an example of the frame structure. Streams s₁(t),s₂(t), s₃(t), and s₄(t) correspond to baseband signals 507A, 507B, 507C,and 507D in FIG. 27, namely, constitute the in-phase I component andquadrature Q component of the baseband signal according to the mappingof the modulation scheme such as the QPSK, the 16QAM, and the 64QAM.

As indicated by the frame structure in FIG. 32B, stream s₁(t) indicatess₁(u) of symbol number u, s₁(u+1) of symbol number u+1, . . . .Similarly, the stream s₂(t) indicates s₂(u) of symbol number u, s₂(u+1)of symbol number u+1, . . . . Similarly, the stream s₃(t) indicatess₃(u) of symbol number u, s₃(u+1) of symbol number u+1, . . . .Similarly, the stream s₄(t) indicates s₄(u) of symbol number u, s₄(u+1)at symbol number u+1, . . . .

Weighting unit 1200 receives baseband signals 507A (s₁(t)), 507B(s₂(t)), 507C (s₃(t)), and 507D (s₄(t)) in FIG. 27 and information 515on the signal processing method as input, performs the weightingaccording to information 515 on the signal processing method, andoutputs weighted signals 516A (z₁′(t)), 516B (z₂′(t)), 516C (z₃′(t)),and 516D (z₄′(t)) in FIG. 27.

Phase changing unit 517A changes the phase of weighted signal516A(z₁′(t)), and outputs post-phase change signal 509A(z₁(t)).

Phase changing unit 517B changes the phase of weighted signal516B(z₂′(t)), and outputs post-phase change signal 509B(z₂(t)).

Phase changing unit 517C changes the phase of weighted signal516C(z₃′(t)), and outputs post-phase change signal 509C(z₃(t)).

Phase changing unit 517D changes the phase of weighted signal516D(z₄′(t)) and outputs post-phase change signal 509D(z₄(t)).

Assuming that (w₁,w₁₂,w₁₃,w₁₄) is vector W₁ of a first row in fixedprecoding matrix F, that (s₁(t),s₂(t),s₃(t),s₄(t))^(T) is S(t), and thaty₁(t) is a phase changing equation of the phase changing unit, z₁(t) isexpressed by Equation (55).

[Mathematical formula 55]

z ₁(t)=y ₁(t)W ₁ S(t)  Equation (55)

It is also assumed that A^(T) is a transpose of matrix (or vector) A.

Assuming that (w₂₁,w₂₂,w₂₃,w₂₄) is vector W₂ of a second row in fixedprecoding matrix F and that y₂(t) is the phase changing equation of thephase changing unit, z₂(t) is expressed by Equation (56).

[Mathematical formula 56]

z ₂(t)=y ₂(t)W ₂ S(t)  Equation (56)

Assuming that (w₃₁,w₃₂,w₃₃,w₃₄) is vector W₃ of a third row in fixedprecoding matrix F and that y₃(t) is the phase changing equation of thephase changing unit, z₃(t) is expressed by Equation (57).

[Mathematical formula 57]

z ₃(t)=y ₃(t)W ₃ S(t)  Equation (57)

Assuming that (w₄₁,w₄₂,w₄₃,w₄₄) is vector W of a fourth row in fixedprecoding matrix F and that y₄(t) is the phase changing equation of thephase changing unit, z₄(t) is expressed by Equation (58).

[Mathematical formula 58]

z ₄(t)=y ₄(t)W ₄ S(t)  Equation (58)

The phase changing method is described later.

FIG. 33 illustrates a configuration example of the transmission deviceof the second exemplary embodiment. Wireless unit 1303_X receivesreceived signal 1302_X received by antenna 1301_X as input, performspieces of processing such as the frequency conversion and the quadraturedemodulation, and outputs baseband signal 1304_X.

Channel fluctuation estimator 1305 for modulated signals z₁, z₂, z₃, andz₄ transmitted by the transmission device receives baseband signal1304_X as input, extracts channel estimating reference symbol 1201_1 inFIG. 32B, estimates the value corresponding to h₁₁ of Equation (53), andoutputs channel estimation signal 1306_1.

Channel fluctuation estimator 1305 for modulated signals z₁, z₂, z₃, andz₄ transmitted by the transmission device receives baseband signal1304_X as input, extracts channel estimating reference symbol 1201_2 inFIG. 32B, estimates the value corresponding to h₁₂ of Equation (53), andoutputs channel estimation signal 1306_2.

Channel fluctuation estimator 1305 for modulated signals z₁, z₂, z₃, andz₄ transmitted by the transmission device receives baseband signal1304_X as input, extracts channel estimating reference symbol 1201_3 inFIG. 32B, estimates the value corresponding to h₁₃ of Equation (53), andoutputs channel estimation signal 1306_3.

Channel fluctuation estimator 1305 for modulated signals z₁, z₂, z₃, andz₄ transmitted by the transmission device receives baseband signal1304_X as input, extracts channel estimating reference symbol 1201_4 inFIG. 32B, estimates the value corresponding to h₁₄ of Equation (53), andoutputs channel estimation signal 1306_4.

Wireless unit 1303_Y receives received signal 1302_Y received by antenna1301_Y as input, performs pieces of processing such as the frequencyconversion and the quadrature demodulation, and outputs baseband signal1304_Y.

Channel fluctuation estimator 1307 for modulated signals z₁, z₂, z₃, andz₄ transmitted by the transmission device receives baseband signal1304_Y as input, extracts channel estimating reference symbol 1201_1 inFIG. 32B, estimates the value corresponding to h₂₁ of Equation (53), andoutputs channel estimation signal 1306_1.

Channel fluctuation estimator 1307 for modulated signals z₁, z₂, z₃, andz₄ transmitted by the transmission device receives baseband signal1304_Y as input, extracts channel estimating reference symbol 1201_2 inFIG. 32B, estimates the value corresponding to h₂₂ of Equation (53), andoutputs channel estimation signal 1306_2.

Channel fluctuation estimator 1307 for modulated signals z₁, z₂, z₃, andz₄ transmitted by the transmission device receives baseband signal1304_Y as input, extracts channel estimating reference symbol 1201_3 inFIG. 32B, estimates the value corresponding to h₂₃ of Equation (53), andoutputs channel estimation signal 1306_3.

Channel fluctuation estimator 1307 for modulated signals z₁, z₂, z₃, andz₄ transmitted by the transmission device receives baseband signal1304_Y as input, extracts channel estimating reference symbol 1201_4 inFIG. 32B, estimates the value corresponding to h₂₄ of Equation (53), andoutputs channel estimation signal 1306_4.

Wireless unit 1303_Z receives received signal 1302_Z received by antenna1301_Z as input, performs pieces of processing such as the frequencyconversion and the quadrature demodulation, and outputs baseband signal1304_Z.

Channel fluctuation estimator 1309 for modulated signals z₁, z₂, z₃, andz₄ transmitted by the transmission device receives baseband signal1304_Z as input, extracts channel estimating reference symbol 1201_1 inFIG. 32B, estimates the value corresponding to h₃₁ of Equation (53), andoutputs channel estimation signal 1310_1.

Channel fluctuation estimator 1309 for modulated signals z₁, z₂, z₃, andz₄ transmitted by the transmission device receives baseband signal1304_Z as input, extracts channel estimating reference symbol 1201_2 inFIG. 32B, estimates the value corresponding to h₃₂ of Equation (53), andoutputs channel estimation signal 1310_2.

Channel fluctuation estimator 1309 for modulated signals z₁, z₂, z₃, andz₄ transmitted by the transmission device receives baseband signal1304_Z as input, extracts channel estimating reference symbol 1201_3 inFIG. 32B, estimates the value corresponding to h₃₃ of Equation (53), andoutputs channel estimation signal 1310_3.

Channel fluctuation estimator 1309 for modulated signals z₁, z₂, z₃, andz₄ transmitted by the transmission device receives baseband signal1304_Z as input, extracts channel estimating reference symbol 1201_4 inFIG. 32B, estimates the value corresponding to h₃₄ of Equation (53), andoutputs channel estimation signal 1310_4.

Wireless unit 1303_H receives received signal 1302_H received by antenna1301_H as input, performs pieces of processing such as the frequencyconversion and the quadrature demodulation, and outputs baseband signal1304_H.

Channel fluctuation estimator 3301 for modulated signals z₁, z₂, z₃, andz₄ transmitted by the transmission device receives baseband signal1304_H as input, extracts channel estimating reference symbol 1201_1 inFIG. 32B, estimates the value corresponding to h₄₁ of Equation (53), andoutputs channel estimation signal 3302_1.

Channel fluctuation estimator 3301 for modulated signals z₁, z₂, z₃, andz₄ transmitted by the transmission device receives baseband signal1304_H as input, extracts channel estimating reference symbol 1201_2 inFIG. 32B, estimates the value corresponding to h₄₂ of Equation (53), andoutputs channel estimation signal 3302_2.

Channel fluctuation estimator 3301 for modulated signals z₁, z₂, z₃, andz₄ transmitted by the transmission device receives baseband signal1304_H as input, extracts channel estimating reference symbol 1201_3 inFIG. 32B, estimates the value corresponding to h₄₃ of Equation (53), andoutputs channel estimation signal 3302_3.

Channel fluctuation estimator 3301 for modulated signals z₁, z₂, z₃, andz₄ transmitted by the transmission device receives baseband signal1304_H as input, extracts channel estimating reference symbol 1201_4 inFIG. 32B, estimates the value corresponding to h₄₄ of Equation (53), andoutputs channel estimation signal 3302_4.

Control information decoder 1311 receives baseband signals 1304_X,1304_Y, 1304_Z, and 1304_H as input, detects symbol 1000_1 posting thetransmission method in FIG. 30, and outputs signal 1312 related to theinformation on the transmission method posted by the transmissiondevice.

Signal processor 1313 receives baseband signals 1304_X, 1304_Y, 1304_Z,and 1304_H, channel estimation signals 1306_1, 1306_2, 1306_3, 1306_4,1306_1, 1306_2, 1306_3, 1306_4, 1310_1, 1310_2, 1310_3, 1310_4, 3302_1,3302_2, 3302_3, and 1310_4, and signal 1312 related to the informationon the transmission method posted by the transmission device, performsML (Maximum Likelihood) detection, performs (error correction) decoding,and outputs received data 1314_1, and/or 1314_2, and/or 1314_3, and/or1314_4.

The operation of signal processor 1313 in FIG. 33 will be supplemented.For example, it is assumed that signal processor 1313 performs the MLD(Maximum Likelihood Detection) processing described in NPLs 8, 9, and10.

The transmission method of the present exemplary embodiment is a MIMOtransmission method, in which the signal phase is regularly changedtogether with the time while the precoding matrix is used.

Assuming that H(t) is the (channel) matrix in Equation (53), that F isthe precoding weight matrix, that Y(t) (at this point, Y(t) depends ont) is the matrix of the phase changing equation of the phase changingunit in FIG. 32A, that (r₁(t),r₂(t),r₃(t),r₄(t))^(T) is received vectorR(t), and that (s₁(t),s₂(t),s₃(t),s₄(t))^(T) is stream vector S(t),Equation (59) holds.

[Mathematical  formula  59] $\begin{matrix}{{{R(t)} = {{H(t)} \times {Y(t)} \times F \times {S(t)}}}{Where}{{Y(t)} = \begin{pmatrix}{y_{1}(t)} & 0 & 0 & 0 \\0 & {y_{2}(t)} & 0 & 0 \\0 & 0 & {y_{3}(t)} & 0 \\0 & 0 & 0 & {y_{4}(t)}\end{pmatrix}}} & {{Equation}\mspace{14mu} (59)}\end{matrix}$

a noise component is not described in Equation (59).

At this point, the reception device can perform the MLD on receivedvector R(t) by obtaining H(t)×Y(t)×F.

The operation of the MLD will be described below. In the followingdescription, it is assumed that the modulation schemes of modulatedsignals (streams) s₁, s₂, s₃, and s₄ are the BPSK.

First, (2⁴=16) candidate signal points corresponding to baseband signal1304_X are obtained from channel estimation signals 1306_1, 1306_2,1306_3, and 1306_4. FIG. 34 illustrates the state at that time. In FIG.34, the mark ● (black circle) indicates the candidate signal point onthe I-Q plane, and the 16 candidate signal points exist because of foursystems of the BPSK. Assuming that b0 is 1 bit transmitted usingmodulated signal s₁, that b1 is 1 bit transmitted using modulated signals₂, that b2 is 1 bit transmitted using modulated signal s₃, and that b3is 1 bit transmitted using modulated signal s₄, the candidate signalpoints corresponding to (b0,b1,b2,b3) exist in FIG. 34.

A square Euclidean distance between received signal point 3401(corresponding to baseband signal 1304_X) and each of the candidatesignal points is obtained. Each square Euclidean distance is divided bynoise variance σ². Accordingly, E_(X)(b0,b1,b2,b3) is obtained bydividing the square Euclidean distance between each of the candidatesignal points corresponding to (b0,b1,b2,b3) and the received signalpoint by the noise variance, namely, E_(X)(1,1,1,1) is obtained fromE_(X)(0,0,0,0). The baseband signals and modulated signals s₁, s₂, s₃,and s₄ are complex signals.

Similarly, (2⁴=16) candidate signal points corresponding to basebandsignal 1304_Y are obtained from channel estimation signals 1306_1,1306_2, 1306_3, and 1306_4. FIG. 34 illustrates the state at that time.In FIG. 34, the mark ● (black circle) indicates the candidate signalpoint on the I-Q plane, and the 16 candidate signal points exist becauseof four systems of the BPSK. Assuming that b0 is 1 bit transmitted usingmodulated signal s₁, that b1 is 1 bit transmitted using modulated signals₂, that b2 is 1 bit transmitted using modulated signal s₃, and that b3is 1 bit transmitted using modulated signal s₄, the candidate signalpoints corresponding to (b0,b1,b2,b3) exist in FIG. 34. (However, thestate in FIG. 34 is illustrated only by way of example.)

The square Euclidean distance between received signal point 3401(corresponding to baseband signal 1304_Y) and each of the candidatesignal points is obtained. Each square Euclidean distance is divided bynoise variance σ². Accordingly, E_(Y)(b0,b1,b2,b3) is obtained bydividing the square Euclidean distance between each of the candidatesignal points corresponding to (b0,b1,b2,b3) and the received signalpoint by the noise variance, namely, E_(Y)(1,1,1,1) is obtained fromE_(Y)(0,0,0,0). The baseband signals and modulated signals s₁, s₂, s₃,and s₄ are complex signals.

Similarly, (2⁴=16) candidate signal points corresponding to basebandsignal 1304_Z are obtained from channel estimation signals 1310_1,1310_2, 1310_3, and 1310_4. FIG. 34 illustrates the state at that time.In FIG. 34, the mark ● (black circle) indicates the candidate signalpoint on the I-Q plane, and the 16 candidate signal points exist becauseof four systems of the BPSK. Assuming that b0 is 1 bit transmitted usingmodulated signal s₁, that b1 is 1 bit transmitted using modulated signals₂, that b2 is 1 bit transmitted using modulated signal s₃, and that b3is 1 bit transmitted using modulated signal s₄, the candidate signalpoints corresponding to (b0,b1,b2,b3) exist in FIG. 34. (However, thestate in FIG. 34 is illustrated only by way of example.)

The square Euclidean distance between received signal point 3401(corresponding to baseband signal 1304_Z) and each of the candidatesignal points is obtained. Each square Euclidean distance is divided bynoise variance σ². Accordingly, E_(Z)(b0,b1,b2,b3) is obtained bydividing the square Euclidean distance between each of the candidatesignal points corresponding to (b0,b1,b2,b3) and the received signalpoint by the noise variance, namely, E_(Z)(1,1,1,1) is obtained fromE_(Z)(0,0,0,0). The baseband signals and modulated signals s₁, s₂, s₃,and s₄ are complex signals.

Similarly, (2⁴=16) candidate signal points corresponding to basebandsignal 1304_H are obtained from channel estimation signals 3302_1,3302_2, 3302_3, and 3302_4. FIG. 34 illustrates the state at that time.In FIG. 34, the mark ● (black circle) indicates the candidate signalpoint on the I-Q plane, and the 16 candidate signal points exist becauseof four systems of the BPSK. Assuming that b0 is 1 bit transmitted usingmodulated signal s₁, that b1 is 1 bit transmitted using modulated signals₂, that b2 is 1 bit transmitted using modulated signal s₃, and that b3is 1 bit transmitted using modulated signal s₄, the candidate signalpoints corresponding to (b0,b1,b2,b3) exist in FIG. 34. (However, thestate in FIG. 34 is illustrated only by way of example.)

The square Euclidean distance between received signal point 3401(corresponding to baseband signal 1304_H) and each of the candidatesignal points is obtained. Each square Euclidean distance is divided bynoise variance σ². Accordingly, E_(H)(b0,b1,b2,b3) is obtained bydividing the square Euclidean distance between each of the candidatesignal points corresponding to (b0,b1,b2,b3) and the received signalpoint by the noise variance, namely, E_(H)(1,1,1,1) is obtained fromE_(H)(0,0,0,0). The baseband signals and modulated signals s₁, s₂, s₃,and s₄ are complex signals.

E_(X)(b0,b1,b2,b3)+E_(Y)(b0,b1,b2,b3)+E_(Z)(b0,b1,b2,b3)+E_(H)(b0,b1,b2,b3)=E(b0,b1,b2,b3)is obtained.

(The value for (b0,b1,b2,b3)=(0,0,0,0) constitutesE_(X)(0,0,0,0)+E_(Y)(0,0,0,0)+E_(Z)(0,0,0,0)+E_(H)(0,0,0,0)=E(0,0,0,0),the value for (b0,b1,b2,b3)=(0,0,0,1) constitutesE_(X)(0,0,0,1)+E_(Y)(0,0,0,1)+E_(Z)(0,0,0,1)+E_(H)(0,0,0,1)=E(0,0,0,1),. . .the value for (b0,b1,b2,b3)=(1,1,1,1) constitutesE_(X)(1,1,1,1)+E_(Y)(1,1,1,1)+E_(Z)(1,1,1,1)+E_(H)(1,1,1,1)=E(1,1,1,1)).

For example, the logarithmic likelihood ratio of each bit is obtainedfrom E(b0,b1,b2,b3), the logarithmic likelihood ratios are rearranged(interleaved), the error correction decoding is performed using therearranged logarithmic likelihood ratio, and received data 1314_1,and/or 1314_2, and/or 1314_3, and/or 1314_4 is output.

The degradation of the reception quality in the present disclosure willbe described below. It is considered that the reception device in FIG.33 performs the reception. FIG. 35 illustrates an example (the state ofthe candidate signal point) of the reception state of the I-Q plane insignal processor 1313 of FIG. 33. In FIG. 35, the mark ● (black circle)indicates the candidate signal point on the IQ plane, b0 is transmittedusing s₁(t), b1 is transmitted using s₂(t), b2 is transmitted usings₃(t), and b3 is transmitted using s₄(t). Therefore, ideally the 16candidate signal points exist as illustrated in FIG. 35. (The candidatesignal points in which (b0,b1,b2,b3) corresponds to (0,0,0,0) to(1,1,1,1) exist.)

FIG. 36 illustrates an example (the state of the candidate signal point)of the reception state of the I-Q plane in signal processor 1313 of FIG.33. In FIG. 36, the mark ● (black circle) indicates the candidate signalpoint on the IQ plane.

Candidate signal point 3602 is the candidate signal point in which(b0,b1,b2,b3) corresponds to (0,0,0,0).

Candidate signal point 3603 is the candidate signal point in which(b0,b1,b2,b3) corresponds to (0,0,0,1) and (0,1,0,0).

Candidate signal point 3604 is the candidate signal point in which(b0,b1,b2,b3) corresponds to (0,1,0,1).

Candidate signal point 3605 is the candidate signal point in which(b0,b1,b2,b3) corresponds to (1,1,0,1) and (0,1,1,1).

Candidate signal point 3606 is the candidate signal point in which(b0,b1,b2,b3) corresponds to (1,1,1,1).

Candidate signal point 3607 is the candidate signal point in which(b0,b1,b2,b3) corresponds to (1,1,1,0) and (1,0,1,1).

Candidate signal point 3608 is the candidate signal point in which(b0,b1,b2,b3) corresponds to (1,0,1,0).

Candidate signal point 3609 is the candidate signal point in which(b0,b1,b2,b3) corresponds to (1,0,0,0) and (0,0,1,0).

Candidate signal point 3610 is the candidate signal point in which(b0,b1,b2,b3) corresponds to (0,0,1,1), (0,1,1,0), (1,1,0,0), and(1,0,0,1).

In FIG. 36, the number of candidate signal points decreases comparedwith the ideal state in FIG. 35. When the reception is performed in thestate of FIG. 36, the data reception quality degrades in the receptiondevice. Particularly, in an environment where a direct wave is dominant,a propagation environment is steady because of a strong influence of thedirect wave, which results in a phenomenon in which the low datareception quality continues for a long time. In FIG. 36, by way ofexample, the candidate signal points overlap each other. For example,similarly the decreases of the minimum Euclidean distances of the 16candidate signal points lead to the degradation of the data receptionquality. (Particularly, there is a high possibility of generating thedegradation of the data reception quality in the environment where thedirect wave is dominant).

The phenomenon in which the candidate signal points overlap each otheris also generated in the case that the four baseband signals, namely,s₁(t), s₂(t), s₃(t), and s₄(t) exist. The method for improving the datareception quality in the case that “particularly, in the environmentwhere the direct wave is dominant, the propagation environment is steadybecause of the strong influence of the direct wave, which results in thephenomenon in which the low data reception quality continues for a longtime” will be described below.

FIG. 37 illustrates specific examples of the phase change values inphase changing units 517A, 517B, 517C, and 517D of the transmissiondevice in FIGS. 27 and 28. As described above, it is assumed that y₁(t)is the phase change value of phase changing unit 517A, that y₂(t) is thephase change value of phase changing unit 517B, that y₃(t) is the phasechange value of phase changing unit 517C, and that y₄(t) is the phasechange value of phase changing unit 517D. In FIG. 37, t is the time(although y₁(t), y₂(t), y₃(t), and y₄(t) are the function of the time inthis case, the phase change value may be the function of the frequencyor the frequency and time as described above), “0” means the 0 radian,“a” means the a radian, “b” means the b radian. It is assumed that where0≤a<2π, 0≤b<2π, a≠0, b≠0, and a≠b.

As illustrated in FIG. 37, it is assumed that

-   -   at clock time t=0, y₁(0)=0 (radian), y₂(0)=0 (radian), y₃(0)=0        (radian), y₄(0)=0 (radian)    -   at clock time t=1, y₁(1)=0 (radian), y₂(1)=a (radian), y₃(1)=0        (radian), y₄(0)=0 (radian)    -   at clock time t=2, y₁(2)=0 (radian), y₂(2)=b (radian), y₃(2)=0        (radian), y₄(0)=0 (radian)    -   at clock time t=3, y₁(3)=0 (radian), y₂(3)=0 (radian), y₃(3)=0        (radian), y₄(0)=0 (radian)    -   at clock time t=4, y₁(4)=0 (radian), y₂(4)=a (radian), y₃(4)=0        (radian), y₄(0)=0 (radian)    -   at clock time t=5, y₁(5)=0 (radian), y₂(5)=b (radian), y₃(5)=0        (radian), y₄(0)=0 (radian).

In FIG. 37, it is assumed that there are three periods with respect tothe phase change. Accordingly,

-   -   at clock time t=3k, y₁(3k)=0 (radian), y₂(3k)=0 (radian),        y₃(3k)=0 (radian), y₄(3k)=0 (radian)    -   at clock time t=3k+1, y₁(3k+1)=0 (radian), y₂(3k+1)=a (radian),        y₃(3k+1)=0 (radian), y₄(3k+1)=0 (radian)    -   at clock time t=3k+2, y₁(3k+2)=0 (radian), y₂(3k+2)=b (radian),        y₃(3k+2)=0 (radian), y₄(3k+2)=0 (radian)        are obtained. For example, k is an integer of 0 or more.

The degradation of the data reception quality in performing the phasechange in FIG. 37 will be described below.

For example, it is considered that the reception device in FIG. 33receives the modulated signal transmitted from antenna 512B with the lowreception field strength when the reception device in FIG. 33 receivesthe modulated signal transmitted by the transmission device in FIGS. 27and 28. In the following description, it is assumed that the modulationschemes of modulated signals (streams) s₁, s₂, s₃, and s₄ are the BPSK.Accordingly, in the case that the candidate signal points do not overlapeach other in performing the MLD, the 16 candidate signal points emergeon the I-Q plane.

As described above, it is considered that the reception device in FIG.33 receives the modulated signal transmitted from antenna 512B with thelow reception field strength. It is considered that the minimumEuclidean distance is short at the 16 candidate signal points to degradethe data reception quality when the MLD is performed in the environmentin which the direct wave is dominant. It is considered that the casephase change in FIG. 37 is performed under the environment.

In this case, the signal having an influence on the reception state ofthe reception device in FIG. 33 becomes the modulated signalstransmitted from antennas 512A, 512C, and 512D of the transmissiondevice in FIGS. 27 and 28.

In the case that the phase change in FIG. 37 is performed, the phasechange is not performed on the modulated signal transmitted from antenna512A of the transmission device in FIGS. 27 and 28, and the phase changeis not performed on the modulated signal transmitted from antenna 512Cof the transmission device in FIGS. 27 and 28. The phase change is notperformed on the modulated signal transmitted from antenna 512D of thetransmission device in FIGS. 27 and 28. Accordingly, in FIG. 33, thereis a high possibility that the state of the candidate signal point onthe I-Q plane is not largely changed with respect to time t. (There is ahigh possibility of slightly changing the minimum Euclidean distance ofthe candidate signal point.) Therefore, there is a possibility ofretaining the state in the case that the data reception quality degradesin the reception device of FIG. 33.

FIG. 38 illustrates an example of the phase changing method with respectto the above state. FIG. 38 illustrates specific examples of the phasechange values in phase changing units 517A, 517B, 517C, and 517D of thetransmission device in FIGS. 27 and 28. As described above, it isassumed that y₁(t) is the phase change value of phase changing unit517A, that y₂(t) is the phase change value of phase changing unit 517B,that y₃(t) is the phase change value of phase changing unit 517C, andthat y₄(t) is the phase change value of phase changing unit 517D. InFIG. 37, t is the time (although y₁(t), y₂(t), y₃(t), and y₄(t) are thefunction of the time in this case, the phase change value may be thefunction of the frequency or the frequency and time as described above),“0” means the 0 radian, “a” means the a radian, “b” means the b radian.It is assumed that where 0<a<2π, 0<b<2π, a≠0, b≠0, and a≠b.

As illustrated in FIG. 18, it is assumed that

-   -   at clock time t=0, y₁(0)=0 (radian), y₂(0)=0 (radian), y₃(0)=0        (radian), y₄(0)=0 (radian)    -   at clock time t=1, y₁(1)=0 (radian), y₂(1)=a (radian), y₃(1)=0        (radian), y₄(1)=0 (radian)    -   at clock time t=2, y₁(2)=0 (radian), y₂(2)=b (radian), y₃(2)=0        (radian), y₄(2)=0 (radian)    -   at clock time t=3, y₁(3)=0 (radian), y₂(3)=0 (radian), y₃(3)=a        (radian), y₄(3)=0 (radian)    -   at clock time t=4, y₁(4)=0 (radian), y₂(4)=0 (radian), y₃(4)=b        (radian), y₄(4)=0 (radian)    -   at clock time t=5, y₁(5)=0 (radian), y₂(5)=0 (radian), y₃(5)=0        (radian), y₄(5)=a (radian)    -   at clock time t=6, y₁(6)=0 (radian), y₂(6)=0 (radian), y₃(6)=0        (radian), y₄(6)=b (radian)    -   at clock time t=7, y₁(7)=0 (radian), y₂(7)=a (radian), y₃(7)=0        (radian), y₄(7)=a (radian)    -   at clock time t=8, y₁(8)=0 (radian), y₂(8)=a (radian), y₃(8)=0        (radian), y₄(8)=b (radian)    -   at clock time t=9, y₁(9)=0 (radian), y₂(9)=b (radian), y₃(9)=0        (radian), y₄(9)=a (radian)    -   at clock time t=10, y₁(10)=0 (radian), y₂(10)=b (radian),        y₃(10)=0 (radian), y₄(10)=b (radian)    -   at clock time t=11, y₁(11)=0 (radian), y₂(11)=0 (radian),        y₃(11)=a (radian), y₄(11)=a (radian)    -   at clock time t=12, y₁(12)=0 (radian), y₂(12)=0 (radian),        y₃(12)=a (radian), y₄(12)=b (radian)    -   at clock time t=13, y₁(13)=0 (radian), y₂(13)=0 (radian),        y₃(13)=b (radian), y₄(13)=a (radian)    -   at clock time t=14, y₁(14)=0 (radian), y₂(14)=0 (radian),        y₃(14)=b (radian), y₄(14)=b (radian)    -   at clock time t=15, y₁(15)=0 (radian), y₂(15)=a (radian),        y₃(15)=a (radian), y₄(15)=0 (radian)    -   at clock time t=16, y₁(16)=0 (radian), y₂(16)=a (radian),        y₃(16)=b (radian), y₄(16)=0 (radian)    -   at clock time t=17, y₁(17)=0 (radian), y₂(17)=a (radian),        y₃(17)=a (radian), y₄(17)=a (radian)    -   at clock time t=18, y₁(18)=0 (radian), y₂(18)=a (radian),        y₃(18)=a (radian), y₄(18)=b (radian)    -   at clock time t=19, y₁(19)=0 (radian), y₂(19)=a (radian),        y₃(19)=b (radian), y₄(19)=a (radian)    -   at clock time t=20, y₁(20)=0 (radian), y₂(20)=a (radian),        y₃(20)=b (radian), y₄(20)=b (radian)    -   at clock time t=21, y₁(21)=0 (radian), y₂(21)=b (radian),        y₃(21)=a (radian), y₄(21)=0 (radian)    -   at clock time t=22, y₁(22)=0 (radian), y₂(22)=b (radian),        y₃(22)=b (radian), y₄(22)=0 (radian)    -   at clock time t=23, y₁(23)=0 (radian), y₂(23)=b (radian),        y₃(23)=a (radian), y₄(23)=a (radian)    -   at clock time t=24, y₁(24)=0 (radian), y₂(24)=b (radian),        y₃(24)=a (radian), y₄(24)=b (radian)    -   at clock time t=25, y₁(25)=0 (radian), y₂(25)=b (radian),        y₃(25)=b (radian), y₄(25)=a (radian)    -   at clock time t=26, y₁(26)=0 (radian), y₂(26)=b (radian),        y₃(26)=b (radian), y₄(26)=b (radian)    -   at clock time t=27, y₁(27)=0 (radian), y₂(27)=0 (radian),        y₃(27)=0 (radian), y₄(27)=0 (radian), . . . .

In FIG. 38, it is assumed that there are 27 periods with respect to thephase change. Accordingly,

-   -   at clock time t=27×k, y₁(27×k)=0 (radian), y₂(27×k)=0 (radian),        y₃(27×k)=0 (radian), y₄(27×k)=0 (radian)    -   at clock time t=27×k+1, y₁(27×k+1)=0 (radian), y₂(27×k+1)=a        (radian), y₃(27×k+1)=0 (radian), y₄(27×k+1)=0 (radian)    -   at clock time t=27×k+2, y₁(27×k+2)=0 (radian), y₂(27×k+2)=b        (radian), y₃(27×k+2)=0 (radian), y₄(27×k+2)=0 (radian)    -   at clock time t=27×k+3, y₁(27×k+3)=0 (radian), y₂(27×k+3)=0        (radian), y₃(27×k+3)=a (radian), y₄(27×k+3)=0 (radian)    -   at clock time t=27×k+4, y₁(27×k+4)=0 (radian), y₂(27×k+4)=0        (radian), y₃(27×k+4)=b (radian), y₄(27×k+4)=0 (radian)    -   at clock time t=27×k+5, y₁(27×k+5)=0 (radian), y₂(27×k+5)=0        (radian), y₃(27×k+5)=0 (radian), y₄(27×k+5)=a (radian)    -   at clock time t=27×k+6, y₁(27×k+6)=0 (radian), y₂(27×k+6)=0        (radian), y₃(27×k+6)=0 (radian), y₄(27×k+6)=b (radian)    -   at clock time t=27×k+7, y₁(27×k+7)=0 (radian), y₂(27×k+7)=a        (radian), y₃(27×k+7)=0 (radian), y₄(27×k+7)=a (radian)    -   at clock time t=27×k+8, y₁(27×k+8)=0 (radian), y₂(27×k+8)=a        (radian), y₃(27×k+8)=0 (radian), y₄(27×k+8)=b (radian)    -   at clock time t=27×k+9, y₁(27×k+9)=0 (radian), y₂(27×k+9)=b        (radian), y₃(27×k+9)=0 (radian), y₄(27×k+9)=a (radian)    -   at clock time t=27×k+10, y₁(27×k+10)=0 (radian), y₂(27×k+10)=b        (radian), y₃(27×k+10)=0 (radian), y₄(27×k+10)=b (radian)    -   at clock time t=27×k+11, y₁(27×k+11)=0 (radian), y₂(27×k+11)=0        (radian), y₃(27×k+11)=a (radian), y₄(27×k+11)=a (radian)    -   at clock time t=27×k+12, y₁(27×k+12)=0 (radian), y₂(27×k+12)=0        (radian), y₃(27×k+12)=a (radian), y₄(27×k+12)=b (radian)    -   at clock time t=27×k+13, y₁(27×k+13)=0 (radian), y₂(27×k+13)=0        (radian), y₃(27×k+13)=b (radian), y₄(27×k+13)=a (radian)    -   at clock time t=27×k+14, y₁(27×k+14)=0 (radian), y₂(27×k+14)=0        (radian), y₃(27×k+14)=b (radian), y₄(27×k+14)=b (radian)    -   at clock time t=27×k+15, y₁(27×k+15)=0 (radian), y₂(27×k+15)=a        (radian), y₃(27×k+15)=a (radian), y₄(27×k+15)=0 (radian)    -   at clock time t=27×k+16, y₁(27×k+16)=0 (radian), y₂(27×k+16)=a        (radian), y₃(27×k+16)=b (radian), y₄(27×k+16)=0 (radian)    -   at clock time t=27×k+17, y₁(27×k+17)=0 (radian), y₂(27×k+17)=a        (radian), y₃(27×k+17)=a (radian), y₄(27×k+17)=a (radian)    -   at clock time t=27×k+18, y₁(27×k+18)=0 (radian), y₂(27×k+18)=a        (radian), y₃(27×k+18)=a (radian), y₄(27×k+18)=b (radian)    -   at clock time t=27×k+19, y₁(27×k+19)=0 (radian), y₂(27×k+19)=a        (radian), y₃(27×k+19)=b (radian), y₄(27×k+19)=a (radian)    -   at clock time t=27×k+20, y₁(27×k+20)=0 (radian), y₂(27×k+20)=a        (radian), y₃(27×k+20)=b (radian), y₄(27×k+20)=b (radian)    -   at clock time t=27×k+21, y₁(27×k+21)=0 (radian), y₂(27×k+21)=b        (radian), y₃(27×k+21)=a (radian), y₄(27×k+21)=0 (radian)    -   at clock time t=27×k+22, y₁(27×k+22)=0 (radian), y₂(27×k+22)=b        (radian), y₃(27×k+22)=b (radian), y₄(27×k+22)=0 (radian)    -   at clock time t=27×k+23, y₁(27×k+23)=0 (radian), y₂(27×k+23)=b        (radian), y₃(27×k+23)=a (radian), y₄(27×k+23)=a (radian)    -   at clock time t=27×k+24, y₁(27×k+24)=0 (radian), y₂(27×k+24)=b        (radian), y₃(27×k+24)=a (radian), y₄(27×k+24)=b (radian)    -   at clock time t=27×k+25, y₁(27×k+25)=0 (radian), y₂(27×k+25)=b        (radian), y₃(27×k+25)=b (radian), y₄(27×k+25)=a (radian)    -   at clock time t=27×k+26, y₁(27×k+26)=0 (radian), y₂(27×k+26)=b        (radian), y₃(27×k+26)=b (radian), y₄(27×k+26)=b (radian) are        obtained. For example, k is an integer of 0 or more.

An advantage of the phase change in FIG. 38 will be described below.

Similarly to the description in FIG. 37, for example, it is consideredthat the reception device in FIG. 33 receives the modulated signaltransmitted from antenna 512B with the low reception field strength whenthe reception device in FIG. 33 receives the modulated signaltransmitted by the transmission device in FIGS. 27 and 28. In thefollowing description, it is assumed that the modulation schemes ofmodulated signals (streams) s₁, s₂, s₃, and s₄ are the BPSK.Accordingly, in the case that the candidate signal points do not overlapeach other in performing the MLD, the 16 candidate signal points emergeon the I-Q plane.

As described above, it is considered that the reception device in FIG.33 receives the modulated signal transmitted from antenna 512B with thelow reception field strength. It is considered that the minimumEuclidean distance is short at the 16 candidate signal points to degradethe data reception quality when the MLD is performed in the environmentin which the direct wave is dominant. It is considered that the casephase change in FIG. 38 is performed under the environment.

In this case, the signal having an influence on the reception state ofthe reception device in FIG. 33 becomes the modulated signalstransmitted from antennas 512A, 512C, and 512D of the transmissiondevice in FIGS. 27 and 28.

In the case that the phase change in FIG. 38 is performed, the phasechange is not performed on the modulated signal transmitted from antenna512A of the transmission device in FIGS. 27 and 28 at times t=0, t=1,and t=2, and the phase change is not performed on the modulated signaltransmitted from antenna 512C of the transmission device in FIGS. 27 and28 at times t=0, t=1, and t=2. The phase change is not performed on themodulated signal transmitted from antenna 512D of the transmissiondevice in FIGS. 27 and 28.

Accordingly, in FIG. 33, there is a high possibility that the state ofthe candidate signal point on the I-Q plane is not largely changed attimes t=0, t=1, and t=2. (There is a high possibility of slightlychanging the minimum Euclidean distance of the candidate signal point.)

At times t=3 to t=26, the phase except for 0 (zero) radian is providedin the modulated signal transmitted from antenna 512C of thetransmission device in FIGS. 27 and 28, and the phase except for 0(zero) radian is provided in the modulated signal transmitted fromantenna 512D. Therefore, at times t=3 to t=26, there is a possibility ofimproving the state of the candidate signal point on the I-Q plane (theminimum Euclidean distance of the candidate signal point increases).

When compared with the phase change in FIG. 37, the time for which thecandidate signal point is in good state (the candidate signal point hasthe large minimum Euclidean distance) increases to obtain anadvantageous effect that the reception quality is improved by applyingthe error correction code.

It is considered that the reception device in FIG. 33 receives themodulated signal transmitted from antenna 512C with the low receptionfield strength. It is considered that the minimum Euclidean distance isshort at the 16 candidate signal points to degrade the data receptionquality when the MLD is performed in the environment in which the directwave is dominant. It is considered that the case phase change in FIG. 38is performed under the environment.

In this case, the signal having an influence on the reception state ofthe reception device in FIG. 33 becomes the modulated signalstransmitted from antennas 512A, 512B, and 512D of the transmissiondevice in FIGS. 27 and 28.

In the case that the phase change in FIG. 38 is performed, the phasechange is not performed on the modulated signal transmitted from antenna512A of the transmission device in FIGS. 27 and 28 at times t=0, t=3,and t=4, and the phase change is not performed on the modulated signaltransmitted from antenna 512B of the transmission device in FIGS. 27 and28 at times t=0, t=3, and t=4. The phase change is not performed on themodulated signal transmitted from antenna 512D of the transmissiondevice in FIGS. 27 and 28.

Accordingly, in FIG. 33, there is a high possibility that the state ofthe candidate signal point on the I-Q plane is not largely changed attimes t=0, t=3, and t=4. (There is a high possibility of slightlychanging the minimum Euclidean distance of the candidate signal point.)

However, at times t=1, t=2, t=5 to t=26, the phase except for 0 (zero)radian is provided in the modulated signal transmitted from antenna 512Bof the transmission device in FIGS. 27 and 28, and the phase except for0 (zero) radian is provided in the modulated signal transmitted fromantenna 512D. Therefore, at times t=1, t=2, t=5 to t=26, there is apossibility of improving the state of the candidate signal point on theI-Q plane (the minimum Euclidean distance of the candidate signal pointincreases).

When compared with the phase change in FIG. 37, the time for which thecandidate signal point is in good state (the candidate signal point hasthe large minimum Euclidean distance) increases to obtain anadvantageous effect that the reception quality is improved by applyingthe error correction code.

It is considered that the reception device in FIG. 33 receives themodulated signal transmitted from antenna 512D with the low receptionfield strength. It is considered that the minimum Euclidean distance isshort at the 16 candidate signal points to degrade the data receptionquality when the MLD is performed in the environment in which the directwave is dominant. It is considered that the case phase change in FIG. 38is performed under the environment.

In this case, the signal having an influence on the reception state ofthe reception device in FIG. 33 becomes the modulated signalstransmitted from antennas 512A, 512B, and 512C of the transmissiondevice in FIGS. 27 and 28.

In the case that the phase change in FIG. 38 is performed, the phasechange is not performed on the modulated signal transmitted from antenna512A of the transmission device in FIGS. 27 and 28 at times t=0, t=5,and t=6, and the phase change is not performed on the modulated signaltransmitted from antenna 512B of the transmission device in FIGS. 27 and28 at times t=0, t=5, and t=6. The phase change is not performed on themodulated signal transmitted from antenna 512C of the transmissiondevice in FIGS. 27 and 28.

Accordingly, in FIG. 33, there is a high possibility that the state ofthe candidate signal point on the I-Q plane is not largely changed attimes t=0, t=5, and t=6. (There is a high possibility of slightlychanging the minimum Euclidean distance of the candidate signal point.)

However, at times t=1 to t=4, t=7 to t=26, the phase except for 0 (zero)radian is provided in the modulated signal transmitted from antenna 512Bof the transmission device in FIGS. 27 and 28, and the phase except for0 (zero) radian is provided in the modulated signal transmitted fromantenna 512C. Therefore, at times t=1 to t=4, t=7 to t=26, there is apossibility of improving the state of the candidate signal point on theI-Q plane (the minimum Euclidean distance of the candidate signal pointincreases).

When compared with the phase change in FIG. 37, the time for which thecandidate signal point is in good state (the candidate signal point hasthe large minimum Euclidean distance) increases to obtain anadvantageous effect that the reception quality is improved by applyingthe error correction code.

It is considered that the reception device in FIG. 33 receives themodulated signal transmitted from antenna 512A with the low receptionfield strength. It is considered that the minimum Euclidean distance isshort at the 16 candidate signal points to degrade the data receptionquality when the MLD is performed in the environment in which the directwave is dominant. It is considered that the case phase change in FIG. 38is performed under the environment.

In this case, the signal having an influence on the reception state ofthe reception device in FIG. 33 becomes the modulated signalstransmitted from antennas 512B, 512C, and 512D of the transmissiondevice in FIGS. 27 and 28.

The relative phase relationship among the modulated signal transmittedfrom antenna 512B of the transmission device in FIGS. 27 and 28, themodulated signal transmitted from antenna 512C of the transmissiondevice in FIGS. 27 and 28, the modulated signal transmitted from antenna512D of the transmission device in FIGS. 27 and 28 does not change attimes t=0, t=17, and t=26 in the case that the phase change in FIG. 38is performed. (The phase difference between the modulated signaltransmitted from antenna 512B of the transmission device in FIGS. 27 and28 and the modulated signal transmitted from antenna 512C of thetransmission device in FIGS. 27 and 28 becomes the identical value attimes t=0, t=17, and t=26. The phase difference between the modulatedsignal transmitted from antenna 512B of the transmission device in FIGS.27 and 28 and the modulated signal transmitted from antenna 512D of thetransmission device in FIGS. 27 and 28 becomes the identical value attimes t=0, t=17, and t=26. The phase difference between the modulatedsignal transmitted from antenna 512C of the transmission device in FIGS.27 and 28 and the modulated signal transmitted from antenna 512D of thetransmission device in FIGS. 27 and 28 becomes the identical value attimes t=0, t=17, and t=26.) Accordingly, in FIG. 33, there is a highpossibility that the state of the candidate signal point on the I-Qplane is not largely changed at times t=0, t=17, and t=26. (There is ahigh possibility of slightly changing the minimum Euclidean distance ofthe candidate signal point.) (The state of the candidate signal pointdoes not change in the case that the relative phase relationship doesnot change.)

However, the relative phase relationship among the modulated signaltransmitted from antenna 512B of the transmission device in FIGS. 27 and28, the modulated signal transmitted from antenna 512C of thetransmission device in FIGS. 27 and 28, and the modulated signaltransmitted from antenna 512D of the transmission device in FIGS. 27 and28 changes at times t=1 to t=16, and t=18 to t=25, the plurality ofphases are provided in the modulated signal transmitted from antenna512B of the transmission device in FIGS. 27 and 28, the plurality ofphases are provided in the modulated signal transmitted from antenna512C of the transmission device in FIGS. 27 and 28, and the plurality ofphases are provided in the modulated signal transmitted from antenna512D of the transmission device in FIGS. 27 and 28. Therefore, there isa possibility of improving the state of the candidate signal point onthe I-Q plane (the minimum Euclidean distance of the candidate signalpoint increases) at times t=1 to t=16, and t=18 to t=25.

When compared with the phase change in FIG. 37, the time for which thecandidate signal point is in good state (the candidate signal point hasthe large minimum Euclidean distance) increases to obtain anadvantageous effect that the reception quality is improved by applyingthe error correction code.

Thus, even if any one of the states of transmit antennas 512A, 512B,512C, and 512D in FIGS. 27 and 28 degrades, an advantageous effect thata possibility of degrading the data reception quality is lowered can beobtained.

The example of the phase change and the advantageous effect inperforming the phase change in FIG. 38 are described above. Anotherexample of the phase changing method in which the similar advantageouseffect is obtained will be described below.

It is assumed that a₁ is a value that can be taken by phase change valuey₁(t) of phase changing unit 517A in FIGS. 27 and 28.

It is assumed that m (m is an integer of 2 or more) kinds of values canbe taken by phase change value y₂(t) of phase changing unit 517B inFIGS. 27 and 28, and b_(i) (radian) is the value that can be taken byphase change value y₂(t) (i is an integer between 1 and m (inclusive),and 0<b_(i)<2π). At this point, i and j are integers between 1 and m(inclusive), i≠j, and b_(i)≠b_(j) is satisfied for any i and j.

It is assumed that n (n is an integer of 2 or more) kinds of values canbe taken by phase change value y₃(t) of phase changing unit 517C inFIGS. 27 and 28, and c_(i) (radian) is the value that can be taken byphase change value y₃(t) (i is an integer between 1 and n (inclusive),and 0≤c_(i)<2π). At this point, i and j are integers between 1 and n(inclusive), i≠j, and c_(i)≠c_(j) is satisfied for any i and j.

It is assumed that q (q is an integer of 2 or more) kinds of values canbe taken by phase change value y₄(t) of phase changing unit 517D inFIGS. 27 and 28, and di (radian) is the value that can be taken by phasechange value y₄(t) (i is an integer between 1 and q (inclusive), and0<d_(i)<2π). At this point, i and j are integers between 1 and q(inclusive), i≠j, and d_(i)≠d_(j) is satisfied for any i and j.

Assuming that (a₁,b_(i),c_(j), d_(k)) is a value taken by a set of(y₁(u),y₂(u),y₃(u),y₄(u)) in symbol number u (u is an integer of 0 ormore), the following conditions are satisfied.

(Condition 5)

It is assumed that i=β (β is an integer between 1 and m (inclusive)),and j=γ (γ is an integer between 1 and n (inclusive)) hold. At thispoint, that (y₁(u),y₂(u),y₃(u),y₄(u))=(a₁,b_(β),c_(γ),d_(k)) holds((y₁(u),y₂(u),y₃(u),y₄(u))=(a₁,b_(β),c_(γ),d_(k)) means y₁(u)=a₁,y₂(u)=b_(β), y₃(u)=c_(γ), and y₄(u)=d_(k)). When i=β and j=γ aresatisfied in integer u of 0 or more, k takes all the values of theinteger between 0 and q (inclusive) in d_(k).

(Condition 6)

The condition that “k takes all the values of the integers between 0 andq (inclusive) in d_(k) when i=β and j=γ are satisfied in integer u of 0or more” is satisfied in β of all the integers between 1 and m(inclusive) and γ of all the integers between 1 and n (inclusive).

(Condition 7)

It is assumed that i=β (β is an integer between 1 and m (inclusive)),and k=δ (δ is an integer between 1 and q(inclusive)) hold. At thispoint, that (y₁(u),y₂(u),y₃(u),y₄(u))=(a₁,b_(β),c_(j),d_(δ)) holds((y₁(u),y₂(u),y₃(u),y₄(u))=(a₁,b_(β),c_(j),d_(δ)) means y₁(u)=a₁,y₂(u)=b_(β), y₃(u)=c_(j), and y₄(u)=d_(δ)). When i=β and k=δ aresatisfied in integer u of 0 or more, j takes all the values of theinteger between 0 and n (inclusive) in c_(j).

(Condition 8)

The condition that “j takes all the values of the integers between 0 andn (inclusive) in c_(j) when i=β and k=δ are satisfied in integer u of 0or more” is satisfied in β of all the integers between 1 and m(inclusive) and δ of all the integers between 1 and q (inclusive).

(Condition 9)

It is assumed that j=γ (γ is an integer between 1 and n (inclusive)),and k=δ (δ is an integer between 1 and q (inclusive)) hold. At thispoint, that (y₁(u),y₂(u),y₃(u),y₄(u))=(a₁,b_(i),c_(γ),d_(δ)) holds((y₁(u),y₂(u),y₃(u),y₄(u))=(a₁,b_(i),c_(γ),d_(δ)) means y_(i)(u)=a₁,y₂(u)=b_(i), y₃(u)=c_(γ), and y₄(u)=d_(δ)). When j=γ and k=δ aresatisfied in integer u of 0 or more, i takes all the values of theinteger between 0 and m (inclusive) in b_(i).

(Condition 10)

The condition that “i takes all the values of the integers between 0 andm (inclusive) in b_(i) when j=γ and k=δ are satisfied in integer u of 0or more” is satisfied in γ of all the integers between 1 and n(inclusive) and δ of all the integers between 1 and q (inclusive).

The advantageous effect can be obtained by satisfying (Condition 1) to(Condition 10) when the phase change is performed as illustrated in FIG.38. Although m×n×q is the minimum value of the period of the phasechange satisfying (Condition 1) to (Condition 10), the period of thephase change may be greater than or equal to m×n×q. (In this case, theidentical set of phase changes is used at least twice, and the period ofthe phase change is set under that condition.)

The phase changing method in the case that phase change value y₁(t) ofthe phase changing unit 517A in FIGS. 27 and 28 is set to a constantvalue is described in the example of FIG. 38 and the above example. Thephase changing method in the case that phase change value y₁(t) of thephase changing unit 517A in FIGS. 27 and 28 is changed according to thetime (frequency) (frequency and time) will be described below.

It is assumed that p (p is an integer of 2 or more) kinds of values canbe taken by phase change value y₁(t) of phase changing unit 517A inFIGS. 27 and 28, and a_(i) (radian) is the value that can be taken byphase change value y₁(t) (i is an integer between 1 and p (inclusive),and 0<a_(i)<2π). At this point, i and j are integers between 1 and p(inclusive), i≠j, and a_(i)≠a_(j) is satisfied for any i and j.

It is assumed that m (m is an integer of 2 or more) kinds of values canbe taken by phase change value y₂(t) of phase changing unit 517B inFIGS. 27 and 28, and b_(i) (radian) is the value that can be taken byphase change value y₂(t) (i is an integer between 1 and m (inclusive),and 0<b_(i)<2π). At this point, i and j are integers between 1 and m(inclusive), i≠j, and b_(i) b_(j) is satisfied for any i and j.

It is assumed that n (n is an integer of 2 or more) kinds of values canbe taken by phase change value y₃(t) of phase changing unit 517C inFIGS. 27 and 28, and ci (radian) is the value that can be taken by phasechange value y₃(t) (i is an integer between 1 and n (inclusive), and0<ci<2π). At this point, i and j are integers between 1 and n(inclusive), i≠j, and c_(i)≠c_(j) is satisfied for any i and j.

It is assumed that q (q is an integer of 2 or more) kinds of values canbe taken by phase change value y₄(t) of phase changing unit 517D inFIGS. 27 and 28, and di (radian) is the value that can be taken by phasechange value y₄(t) (i is an integer between 1 and q (inclusive), and0<di<2π). At this point, i and j are integers between 1 and q(inclusive), i≠j, and d_(i)≠d_(j) is satisfied for any i and j.

Assuming that (a_(i),b_(i),c_(k), d_(h)) is a value taken by a set of(y₁(u),y₂(u),y₃(u),y₄(u)) in symbol number u (u is an integer of 0 ormore), the following conditions are satisfied.

(Condition 11)

It is assumed that i=β holds. (β is an integer between 1 and p(inclusive).) At this point, that(y₁(u),y₂(u),y₃(u),y₄(u))=(a_(β),b_(j),c_(k),d_(h)) holds((y₁(u),y₂(u),y₃(u),y₄(u))=(a_(β),b_(j),c_(k),d_(h)) meansy_(i)(u)=a_(β), y₂(u)=b_(i), y₃(u)=c_(k), and y₄(u)=d_(h)). When i=β issatisfied in integer u of 0 or more, in (a_(β),b_(j),c_(k),d_(h)), j isan integer between 0 and m (inclusive), k is an integer between 0 and n(inclusive), h is an integer between 0 and q (inclusive), and a set(j,k,h) that can be taken by (j,k,h) exists.

(Condition 12)

A condition that, “when i=β is satisfied in integer u of 0 or more, in(a_(β),b_(j),c_(k),d_(h)), j is an integer between 0 and m (inclusive),k is an integer between 0 and n (inclusive), h is an integer between 0and q (inclusive), and a set (j,k,h) that can be taken by (j,k,h)exists” is satisfied in β of all the integers between 1 and p(inclusive).

The advantageous effect can be obtained by satisfying (Condition 11) and(Condition 12) when the phase change is performed as illustrated in FIG.38. Although p×q×m×n is the minimum value of the period of the phasechange satisfying (Condition 11) and (Condition 12), the period of thephase change may be greater than or equal to p×q×m×n. (In this case, theidentical set of phase changes is used twice, and the period of thephase change is set under that condition.)

The example in which H(t)×Y(t)×F is obtained to perform the MLD in thereception device is described above. Alternatively, the detection may beperformed using QR decomposition as described in NPL 9.

As described in NPL 11, based on H(t)×Y(t)×F, MMSE (Minimum Mean SquareError) and ZF (Zero Forcing) are linearly calculated to perform thedetection.

Additionally, in the present exemplary embodiment, the single carrierscheme is described by way of example. However, the present disclosureis not limited the single carrier scheme, but may be similarly embodiedfor multi-carrier transmission. Accordingly, for example, when a spreadspectrum communication scheme, an OFDM (Orthogonal Frequency-DivisionMultiplexing) scheme, an SC-FDMA (Single Carrier Frequency DivisionMultiple Access), an SC-OFDM (Single Carrier OrthogonalFrequency-Division Multiplexing) scheme, or a wavelet OFDM schemedescribed in NPL 12 is used, the present disclosure may be similarlyembodied. In the present exemplary embodiment, such a symbol other thanthe data symbol as a pilot symbols (a preamble, a unique word, and thelike) and a symbol transmitting control information may arbitrarily bearranged in the frame.

An example in which the OFDM scheme is used will be described as anexample of a multi-carrier scheme.

FIGS. 39 and 40 illustrate a configuration of the transmission devicewhen the OFDM scheme is used. In FIG. 39, elements operating similarlyto FIGS. 27 and 28 is designated by the identical reference marks.

OFDM scheme-related processor 3901A receives post-phase change signal509A as input, performs processing related to the OFDM scheme, andoutputs transmission signal 3902A. Similarly, OFDM scheme-relatedprocessor 3901B receives post-phase change signal 509B as input andoutputs transmission signal 3902B, OFDM scheme-related processor 3901Creceives post-phase change signal 509C as input and outputs transmissionsignal 3902C, and OFDM scheme-related processor 3901D receivespost-phase change signal 509D as input and outputs transmission signal3902D.

FIG. 41 illustrates a configuration example subsequent to OFDMscheme-related processors 3901A, 3901B, 3901C, and 3901D in FIGS. 39 and40. Components 2101A to 2110A correspond to components 3901A to 512A inFIGS. 39 and 40, components 2101B to 2110B correspond to components3901B to 512B, components 2101C to 2110C correspond to components 3901Cto 512C, and components 2101D to 2110D correspond to components 3901D to512D.

Serial-parallel converter 2102A performs the serial-parallel conversionon weighted signal 2101A (corresponding to weighted signal 509A in FIGS.39 and 40) and outputs parallel signal 2103A.

Rearranger 2104A receives parallel signal 2103A as input, performs therearrangement, and outputs rearranged signal 2105A. The rearrangement isdescribed in detail later.

Inverse fast Fourier transformer 2106A receives rearranged signal 2105Aas input, performs the inverse fast Fourier transform, and outputspost-inverse fast Fourier transform signal 2107A.

Wireless unit 2108A receives post-inverse fast Fourier transform signal2107A as input, performs the pieces of processing such as the frequencyconversion and the amplification, and outputs modulated signal 2109A.Modulated signal 2109A is output as a radio wave from antenna 2110A.

Serial-parallel converter 2102B performs serial-parallel conversion onweighted signal 2101B (corresponding to weighted signal 509B in FIGS. 39and 40) and outputs parallel signal 2103B.

Rearranger 2104B receives parallel signal 2103B as input, performs therearrangement, and outputs rearranged signal 2105B. The rearrangement isdescribed in detail later.

Inverse fast Fourier transformer 2106B receives the rearranged signal2105B as input, performs the inverse fast Fourier transform, and outputspost-inverse fast Fourier transform signal 2107B.

Wireless unit 2108B receives post-inverse fast Fourier transform signal2107B as input, performs the pieces of processing such as the frequencyconversion and the amplification, and outputs modulated signal 2109B.Modulated signal 2109B is output as a radio wave from antenna 2110B.

Serial-parallel converter 2102C performs the serial-parallel conversionon weighted signal 2101C (corresponding to weighted signal 509C in FIGS.39 and 40) and outputs parallel signal 2103C.

Rearranger 2104C receives parallel signal 2103C as input, performs therearrangement, and outputs rearranged signal 2105C. The rearrangement isdescribed in detail later.

Inverse fast Fourier transformer 2106C receives rearranged signal 2105Cas input, performs the inverse fast Fourier transform, and outputspost-inverse fast Fourier transform signal 2107C.

Wireless unit 2108C receives post-inverse fast Fourier transform signal2107C as input, performs the pieces of processing such as the frequencyconversion and the amplification, and outputs modulated signal 2109C.Modulated signal 2109C is output as a radio wave from antenna 2110C.

Serial-parallel converter 2102D performs the serial-parallel conversionon weighted signal 2101D (corresponding to weighted signal 509D in FIGS.39 and 40) and outputs parallel signal 2103D.

Rearranger 2104D receives parallel signal 2103D as input, performs therearrangement, and outputs rearranged signal 2105D. The rearrangement isdescribed in detail later.

Inverse fast Fourier transformer 2106D receives rearranged signal 2105Das input, performs the inverse fast Fourier transform, and outputspost-inverse fast Fourier transform signal 2107D.

Wireless unit 2108D receives post-inverse fast Fourier transform signal2107D as input, performs the pieces of processing such as the frequencyconversion and the amplification, and outputs modulated signal 2109D.Modulated signal 2109D is output as a radio wave from antenna 2110D.

Because the transmission scheme in which the multi-carrier is used isnot adopted in the transmission device in FIGS. 27 and 28, thepost-phase change symbol is disposed in a time axis direction. When suchthe multi-carrier transmission method as the OFDM scheme in FIGS. 39 and40 is adopted, it is conceivable that, for each (sub) carrier, thesymbol that is subjected to the precoding and phase change is disposedin the time axis direction as illustrated in FIGS. 27 and 28. For themulti-carrier transmission scheme, it is also conceivable that thesymbol is disposed in the frequency axis direction, or both thefrequency axis and time axis directions. This point will be describedbelow.

FIG. 42 illustrates an example of the symbol rearranging method on ahorizontal axis indicating the frequency and a vertical axis indicatingthe time in rearrangers 2104A, 2104B, 2104C, and 2104D in FIG. 41. InFIG. 42, the frequency axis is constructed with (sub) carrier 0 to (sub)carrier 9. Modulated signals z₁, z₂, z₃, and z₄ use the identicalfrequency band at the clock time (time). FIG. 42A illustrates a methodfor rearranging the symbol of modulated signal z₁, FIG. 42B illustratesthe method for rearranging the symbol of modulated signal z₂, FIG. 42Cillustrates the method for rearranging the symbol of modulated signalz₃, and FIG. 42D illustrates the method for rearranging the symbol ofmodulated signal z₄.

Numbers #0, #1, #2, #3, . . . are sequentially assigned to the symbol ofweighted and post phase change signal 2101A input to serial-parallelconverter 2102A.

At this point, as illustrated in FIG. 42A, symbols #0, #1, #2, #3, . . .are regularly disposed from carrier 0 such that symbols #0 to #9 aresequentially disposed at clock time $1, and such that symbols #10 to #19are sequentially disposed at clock time $2. Modulated signals z₁, z₂,z₃, and z₄ are complex signals.

Similarly, numbers #0, #1, #2, #3, . . . are assigned to the symbols ofweighted and post phase change signal 2101B which is input toserial-parallel converter 2102B.

At this point, as illustrated in FIG. 42B, symbols #0, #1, #2, #3, . . .are regularly disposed from carrier 0 such that symbols #0 to #9 aresequentially disposed at clock time $1, and such that symbols #10 to #19are sequentially disposed at clock time $2.

Similarly, numbers #0, #1, #2, #3, . . . are sequentially assigned tothe symbol of weighted and post phase change signal 2101C which is inputto serial-parallel converter 2102C.

At this point, as illustrated in FIG. 42C, symbols #0, #1, #2, #3, . . .are regularly disposed from carrier 0 such that symbols #0 to #9 aresequentially disposed at clock time $1, and such that symbols #10 to #19are sequentially disposed at clock time $2.

Similarly, numbers #0, #1, #2, #3, . . . are sequentially assigned tothe symbol of weighted and post phase change signal 2101D which is inputto serial-parallel converter 2102D.

At this point, as illustrated in FIG. 42D, symbols #0, #1, #2, #3, . . .are regularly disposed from carrier 0 such that symbols #0 to #9 aresequentially disposed at clock time $1, and such that symbols #10 to #19are sequentially disposed at clock time $2.

Thus, when such the multi-carrier transmission method as OFDM scheme isused, the symbols can be disposed in the frequency axis direction unlikethe single carrier transmission. The disposition of the symbols is notlimited to that in FIG. 42. Other examples will be described withreference to FIGS. 43 and 44.

FIG. 43 illustrates another example, different from FIG. 42, of thesymbol rearranging method on the horizontal axis indicating thefrequency and the vertical axis indicating the time in rearrangers2104A, 2104B, 2104C, and 2104D in FIG. 41. FIG. 43A illustrates themethod for rearranging the symbol of modulated signal z₁, FIG. 43Billustrates the method for rearranging the symbol of modulated signalz₂, FIG. 43C illustrates the method for rearranging the symbol ofmodulated signal z₃, and FIG. 43D illustrates the method for rearrangingthe symbol of modulated signal z₄. The symbol rearranging method in FIG.43 differs from the symbol rearranging method in FIG. 42 in the methodfor rearranging the symbols of the modulated signals z₁, z₂, z₃, and z₄.In FIG. 43B, symbols #0 to #5 are disposed in carriers 4 to 9, symbols#6 to #9 are disposed in carriers 0 to 3, and symbols #10 to #19 aredisposed in the similar way. In FIG. 43D, symbols #0 to #5 are disposedin carriers 4 to 9, symbols #6 to #9 are disposed in carriers 0 to 3,and symbols #10 to #19 are disposed in the similar way.

FIG. 44 illustrates another example, different from FIG. 42, of thesymbol rearranging method on the horizontal axis indicating thefrequency and the vertical axis indicating the time in rearrangers2104A, 2104B, 2104C, and 2104D in FIG. 41. FIG. 44A illustrates themethod for rearranging the symbol of modulated signal z₁, FIG. 44Billustrates the method for rearranging the symbol of modulated signalz₂, FIG. 44C illustrates the method for rearranging the symbol ofmodulated signal z₃, and FIG. 44D illustrates the method for rearrangingthe symbol of modulated signal z₄. The symbol rearranging method in FIG.44 differs from the symbol rearranging method in FIG. 42 in that thesymbols are not sequentially disposed in FIG. 44 while the symbols aresequentially disposed in FIG. 42. In FIG. 44, similarly to FIG. 43, themethods for rearranging the symbols of the modulated signals z₁, z₂, z₃,and z₄ may differ from one another.

FIG. 45 illustrates another example, different from FIGS. 42 to 44, ofthe symbol rearranging method on the horizontal axis indicating thefrequency and the vertical axis indicating the time in rearrangers2104A, 2104B, 2104C, and 2104D in FIG. 41. FIG. 45A illustrates themethod for rearranging the symbol of modulated signal z₁, FIG. 45Billustrates the method for rearranging the symbol of modulated signalz₂, FIG. 45C illustrates the method for rearranging the symbol ofmodulated signal z₃, and FIG. 45D illustrates the method for rearrangingthe symbol of modulated signal z₄. The symbols are arranged in both thefrequency axis and time axis directions in FIG. 45, while the symbolsare arranged in the frequency axis direction in FIGS. 42 to 44.

FIG. 46 illustrates another example, different from FIG. 45, of thesymbol rearranging method on the horizontal axis indicating thefrequency and the vertical axis indicating the time in rearrangers2104A, 2104B, 2104C, and 2104D in FIG. 41. FIG. 46A illustrates themethod for rearranging the symbol of modulated signal z₁, FIG. 46Billustrates the method for rearranging the symbol of modulated signalz₂, FIG. 46C illustrates the method for rearranging the symbol ofmodulated signal z₃, and FIG. 46D illustrates the method for rearrangingthe symbol of modulated signal z₄. In FIG. 46, similarly to FIG. 45, thesymbols are disposed on both the frequency and time axes. The symbolrearranging method in FIG. 46 differs from the symbol rearranging methodin FIG. 45 in the following point. That is, in FIG. 45, high priority isgiven to the frequency axis direction and then the symbols are disposedon the time axis direction. On the other hand, in FIG. 46, high priorityis given to the time axis direction and then the symbols are disposed onthe frequency axis direction.

Although the symbol disposing methods are described in some drawings,the symbol disposing method is not limited to the above methods. Thesymbol may randomly be disposed on the time-frequency axis, or disposeaccording to a certain rule.

Accordingly, the present exemplary embodiment leads to the followingadvantageous effect. That is, there is a high possibility of improvingthe data reception quality, and particularly there is a high possibilityof largely improving the data reception quality in the LOS environmentin which the direct wave is dominant.

For example, the precoding matrix may be switched when the set ofmodulation schemes of the four streams is switched. The phase changingmethod may be switched when the set of modulation schemes of the fourstreams is switched. The precoding matrix and the phase changing methodmay be switched when the set of modulation schemes of the four streamsis switched (the precoding matrix and the phase changing need not beswitched even if the set of modulation schemes of the four streams isswitched).

For the interleaver, the data need not be rearranged.

Third Exemplary Embodiment

In the first and second exemplary embodiments, as illustrated in FIGS.5, 6, 19, 20, 27, 28, 39, and 40, the mapping, the weighting, and thephase change are sequentially performed by way of example. Amodification in which a phase changing unit or a power changing unit isadded to the first and second exemplary embodiments will be described ina third exemplary embodiment. The phase changing method performed at asubsequent stage of the weighting may be operated similarly to the firstand second exemplary embodiments.

The case that the four streams are transmitted using the four antennasare described in the third exemplary embodiment. In FIGS. 27, 28, 39,and 40, mapping unit 506A to phase changing unit 517A, mapping unit 506Bto phase changing unit 517B, mapping unit 506C to phase changing unit517C, and mapping unit 506D to phase changing unit 517D may be replacedwith those in FIGS. 47, 48, 49, 50, 51, and 52. The operation in eachdrawings will be described below.

FIGS. 47 and 48 are views illustrating a configuration example in whichthe precoding method is performed when average transmission power of thefour transmission signals varies.

In FIG. 47, mapping unit 4704 receives data 4703 and control signal 4714as input. It is assumed that control signal 4714 assigns thetransmission of the four streams as the transmission method.Additionally, it is assumed that control signal 4714 assigns modulationschemes α, β, γ, and δ as the modulation schemes of the four streams.Modulation scheme α modulates p-bit data, modulation scheme β modulatesq-bit data, modulation scheme γ modulates r-bit data, and modulationscheme δ modulates s-bit data. (For example, the modulation schememodulates 4-bit data for the 16QAM, and the modulation scheme modulates6-bit data for the 64QAM.)

Therefore, mapping unit 4704 modulates the p-bit data in (p+q+r+s)-bitdata using modulation scheme α, and generates and outputs basebandsignal s₁(t) (4705A). Mapping unit 4704 modulates the q-bit data usingmodulation scheme β, and generates and outputs baseband signal s₂(t)(4705B). Mapping unit 4704 modulates the r-bit data using modulationscheme γ, and generates and outputs baseband signal s₃(t) (4705C).Mapping unit 4704 modulates the s-bit data using modulation scheme δ,and generates and outputs baseband signal s₄(t) (4705D).

(In FIG. 47, the one mapping unit is described. Alternatively, a mappingunit generating s₁(t) and a mapping unit generating s₂(t) may existseparately. At this point, coded data 4703 is divided into the mappingunit generating s₁(t), the mapping unit generating s₂(t), the mappingunit generating s₃(t), and the mapping unit generating s₄(t). Forexample, as illustrated in FIG. 47, mapping unit 4704 receives pieces ofdata 4703, 4703B, 4703C, and 4703D as input, performs the mapping ondata 4703, and generates and outputs baseband signal s₁(t) (4705A).Mapping unit 4704 also performs the mapping on data 4703B, and generatesand outputs baseband signal s₂(t) (4705B). Mapping unit 4704 alsoperforms the mapping on data 4703C, and generates and outputs basebandsignal s₃(t) (4705C). Mapping unit 4704 also performs the mapping ondata 4703D, and generates and outputs baseband signal s₄(t) (4705D)).

Baseband signals s₁(t), s₂(t), s₃(t), and s₄(t) are expressed by complexnumbers (however, may be either complex numbers or real numbers), and tis a time. For the use of the transmission method in which themulti-carrier such as OFDM (Orthogonal Frequency Division Multiplexing)is used, s₁, s₂, s₃, and s₄ are functions of frequency f such as s₁(f),s₂(f), s₃(f), and s₄(f) or functions of time t and frequency f such ass₁(t,f), s₂(t,f), s₃(t,f), and s₄(t,f).

Hereinafter, the baseband signal, the precoding matrix, and the phasechanging are described as the function of time t. Alternatively, thebaseband signal, the precoding matrix, and the phase changing may beconsidered as the function of frequency f, and the function of time tand frequency f.

Sometimes the baseband signal, the precoding matrix, and the phasechanging are described as the function of symbol number i. In this case,the baseband signal, the precoding matrix, and the phase changing may beconsidered as the function of time t, the function of frequency f, orthe function of time t and frequency f. That is, the symbol and thebaseband signal may be generated and disposed on the time axis directionand the frequency axis direction. The symbol and the baseband signal mayalso be generated and disposed on the time axis direction and thefrequency axis direction.

Power changing unit 4706A (power adjuster 4706A) receives basebandsignal s₁(t) (4705A) and control signal 4714 as input, sets real numberP₁ based on control signal 4714, and outputs P₁×s₁(t) as post-powerchange signal 4707A. (Although P₁ is a real number, P₁ may be a complexnumber.)

Similarly, power changing unit 4706B (power adjuster 4706B) receivesbaseband signal s₂(t) (4705B) and control signal 4714 as input, setsreal number P₂, and outputs P₂×s₂(t) as post-power change signal 4707B.(Although P₂ is a real number, P₂ may be a complex number.)

Similarly, power changing unit 4706C (power adjuster 4706C) receivesbaseband signal s₃(t) (4705C) and control signal 4714 as input, setsreal number P₃, and outputs P₃×s₃(t) as post-power change signal 4707C.(Although P₃ is a real number, P₃ may be a complex number.)

Similarly, power changing unit 4706D (power adjuster 4706D) receivesbaseband signal s₄(t) (4705D) and control signal 4714 as input, setsreal number P₄, and outputs P₄×s₄(t) as post-power change signal 4707D.(Although P₄ is a real number, P₄ may be a complex number.)

Weighting unit 4708 receives post-power change signals 4707A, 4707B,4707C, and 4707D and control signal 4714 as input, and sets precodingmatrix F (or F(i)) based on control signal 4714. Assuming that i is aslot number (symbol number), weighting unit 4708 calculates Equation(60).

     [Mathematical  formula  60] $\begin{matrix}\begin{matrix}{\begin{pmatrix}{u_{1}(i)} \\{u_{2}(i)} \\{u_{3}(i)} \\{u_{4}(i)}\end{pmatrix} = {F \times \begin{pmatrix}{P_{1} \times {s_{1}(i)}} \\{P_{2} \times {s_{2}(i)}} \\{P_{3} \times {s_{3}(i)}} \\{P_{4} \times {s_{4}(i)}}\end{pmatrix}}} \\{= {\begin{pmatrix}a_{11} & a_{12} & a_{13} & a_{14} \\a_{21} & a_{22} & a_{23} & a_{24} \\a_{31} & a_{32} & a_{33} & a_{34} \\a_{41} & a_{42} & a_{43} & a_{44}\end{pmatrix}\begin{pmatrix}{P_{1} \times {s_{1}(i)}} \\{P_{2} \times {s_{2}(i)}} \\{P_{3} \times {s_{3}(i)}} \\{P_{4} \times {s_{4}(i)}}\end{pmatrix}}} \\{= {\begin{pmatrix}a_{11} & a_{12} & a_{13} & a_{14} \\a_{21} & a_{22} & a_{23} & a_{24} \\a_{31} & a_{32} & a_{33} & a_{34} \\a_{41} & a_{42} & a_{43} & a_{44}\end{pmatrix}\begin{pmatrix}P_{1} & 0 & 0 & 0 \\0 & P_{2} & 0 & 0 \\0 & 0 & P_{3} & 0 \\0 & 0 & 0 & P_{4}\end{pmatrix}\begin{pmatrix}{s_{1}(i)} \\{s_{2}(i)} \\{s_{3}(i)} \\{s_{4}(i)}\end{pmatrix}}}\end{matrix} & {{Equation}\mspace{14mu} (60)}\end{matrix}$

Precoding matrix F is already described above using Equations (48) and(49) of the second exemplary embodiment. Precoding matrix F may be afunction of i, or need not be a function of i. When precoding matrix Fis the function of i, precoding matrix F is switched by the slot number(symbol number).

Weighting unit 4708 outputs u₁(i) in Equation (60) as weighted signal4709A, outputs u₂(i) in Equation (60) as weighted signal 4709B, outputsu₃(i) in Equation (60) as weighted signal 4709C, and outputs u₄(i) inEquation (60) as weighted signal 4709D.

Power changing unit 4710A receives weighted signal 4709A (u₁(i)) andcontrol signal 4714 as input, sets real number Q₁ based on controlsignal 4714, and outputs Q₁×u₁(i) as post-power change signal 4711A.(Although Q₁ is a real number, Q1 may be a complex number.)

Similarly, power changing unit 4710B receives weighted signal 4709B(u₂(i)) and control signal 4714 as input, sets real number Q₂ based oncontrol signal 4714, and outputs Q₂×u₂(i) as post-power change signal4711B. (Although Q₂ is a real number, Q₂ may be a complex number.)

Similarly, power changing unit 4710C receives weighted signal 4709C(u₃(i)) and control signal 4714 as input, sets real number Q₃ based oncontrol signal 4714, and outputs Q₃×u₃(i) as post-power change signal4711C. (Although 03 is a real number, Q₃ may be a complex number.)

Similarly, power changing unit 4710D receives weighted signal 4709D(u₄(i)) and control signal 4714 as input, sets real number Q₄ based oncontrol signal 4714, and outputs Q₄×u₄(i) as post-power change signal4711D. (Although Q₄ is a real number, Q₄ may be a complex number.)

Phase changing unit 4712A receives post-power change signal 4711A ofQ₁×u₁(i) and control signal 4714 as input, and changes the phase ofpost-power change signal 4711A of Q₁×u₁(i) based on control signal 4714.Accordingly, the signal in which the phase of post-power change signal4711A of Q₁×u₁(i) is changed is expressed as B₁×e^(jθ1(i))×Q₁×u₁(i), andphase changing unit 4712A outputs B₁×e^(jθ1(i))×Q₁×u₁(i) as post-phasechange signal 4713A (j may be an imaginary unit, and B₁ may be 1.00 or areal number of 0 or more). One of the features of the third exemplaryembodiment is that the value of the changed phase is a function of isuch as θ₁(i). The method for providing θ₁(i) is already described abovein the second exemplary embodiment.

Phase changing unit 4712B receives post-power change signal 4711B ofQ₂×u₂(i) and control signal 4714 as input, and changes the phase ofpost-power change signal 4711B of Q₂×u₂(i) based on control signal 4714.Accordingly, the signal in which the phase of post-power change signal4711B of Q₂×u₂(i) is changed is expressed as B₂×e^(jθ2(i))×Q₂×u₂(i), andphase changing unit 4712B outputs B₂×e^(j2(i))×Q₂×u₂(i) as post-phasechange signal 4713B (j may be an imaginary unit, and B₂ may be 1.00 or areal number of 0 or more). One of the features of the third exemplaryembodiment is that the value of the changed phase is a function of isuch as θ₂(i). The method for providing θ₂(i) is already described abovein the second exemplary embodiment.

Phase changing unit 4712C receives post-power change signal 4711C ofQ₃×u₃(i) and control signal 4714 as input, and changes the phase ofpost-power change signal 4711C of Q₃×u₃(i) based on control signal 4714.Accordingly, the signal in which the phase of post-power change signal4711C of Q₃×u₃(i) is changed is expressed as B₃×e^(jθ3(i))×Q₃×u₃(i), andphase changing unit 4712C outputs B₃×e^(jθ3(i))×Q₃×u₃(i) as post-phasechange signal 4713C (j may be an imaginary unit, and B₃ may be 1.00 or areal number of 0 or more). One of the features of the third exemplaryembodiment is that the value of the changed phase is a function of isuch as θ₃(i). The method for providing θ₃(i) is already described abovein the second exemplary embodiment.

Phase changing unit 4712D receives post-power change signal 4711D ofQ₄×u₄(i) and control signal 4714 as input, and changes the phase ofpost-power change signal 4711D of Q₄×u₄(i) based on control signal 4714.Accordingly, the signal in which the phase of post-power change signal4711D of Q₄×u₄(i) is changed is expressed as B₄×e^(jθ4(i))×Q₄×u₄(i), andphase changing unit 4712D outputs B₄×e^(jθ4(i))×Q₄×u₄(i) as post-phasechange signal 4713D (j may be an imaginary unit, and B₄ may be 1.00 or areal number of 0 or more). One of the features of the third exemplaryembodiment is that the value of the changed phase is a function of isuch as θ₄(i). The method for providing θ₄(i) is already described abovein the second exemplary embodiment.

Therefore, Equation (61) holds.

[Mathematical  formula  61] $\begin{matrix}\begin{matrix}{\begin{pmatrix}{z_{1}(i)} \\{z_{2}(i)} \\{z_{3}(i)} \\{z_{4}(i)}\end{pmatrix} = {\begin{pmatrix}{y_{1}(i)} & 0 & 0 & 0 \\0 & {y_{2}(i)} & 0 & 0 \\0 & 0 & {y_{3}(i)} & 0 \\0 & 0 & 0 & {y_{4}(i)}\end{pmatrix}\begin{pmatrix}Q_{1} & 0 & 0 & 0 \\0 & Q_{2} & 0 & 0 \\0 & 0 & Q_{3} & 0 \\0 & 0 & 0 & Q_{4}\end{pmatrix} \times F \times \begin{pmatrix}{P_{1} \times {s_{1}(i)}} \\{P_{2} \times {s_{2}(i)}} \\{P_{3} \times {s_{3}(i)}} \\{P_{4} \times {s_{4}(i)}}\end{pmatrix}}} \\{= {\begin{pmatrix}{y_{1}(i)} & 0 & 0 & 0 \\0 & {y_{2}(i)} & 0 & 0 \\0 & 0 & {y_{3}(i)} & 0 \\0 & 0 & 0 & {y_{4}(i)}\end{pmatrix}\begin{pmatrix}Q_{1} & 0 & 0 & 0 \\0 & Q_{2} & 0 & 0 \\0 & 0 & Q_{3} & 0 \\0 & 0 & 0 & Q_{4}\end{pmatrix}\begin{pmatrix}a_{11} & a_{12} & a_{13} & a_{14} \\a_{21} & a_{22} & a_{23} & a_{24} \\a_{31} & a_{32} & a_{33} & a_{34} \\a_{41} & a_{42} & a_{43} & a_{44}\end{pmatrix}\begin{pmatrix}{P_{1} \times {s_{1}(i)}} \\{P_{2} \times {s_{2}(i)}} \\{P_{3} \times {s_{3}(i)}} \\{P_{4} \times {s_{4}(i)}}\end{pmatrix}}} \\{= {\begin{pmatrix}{y_{1}(i)} & 0 & 0 & 0 \\0 & {y_{2}(i)} & 0 & 0 \\0 & 0 & {y_{3}(i)} & 0 \\0 & 0 & 0 & {y_{4}(i)}\end{pmatrix}\begin{pmatrix}Q_{1} & 0 & 0 & 0 \\0 & Q_{2} & 0 & 0 \\0 & 0 & Q_{3} & 0 \\0 & 0 & 0 & Q_{4}\end{pmatrix}\begin{pmatrix}a_{11} & a_{12} & a_{13} & a_{14} \\a_{21} & a_{22} & a_{23} & a_{24} \\a_{31} & a_{32} & a_{33} & a_{34} \\a_{41} & a_{42} & a_{43} & a_{44}\end{pmatrix}\begin{pmatrix}P_{1} & 0 & 0 & 0 \\0 & P_{2} & 0 & 0 \\0 & 0 & P_{3} & 0 \\0 & 0 & 0 & P_{4}\end{pmatrix}\begin{pmatrix}{s_{1}(i)} \\{s_{2}(i)} \\{s_{3}(i)} \\{s_{4}(i)}\end{pmatrix}}} \\{= {\begin{pmatrix}{B_{1} \times e^{j\; {{\theta 1}{(i)}}}} & 0 & 0 & 0 \\0 & {B_{2} \times e^{j\; {{\theta 2}{(i)}}}} & 0 & 0 \\0 & 0 & {B_{3} \times e^{j\; {{\theta 3}{(i)}}}} & 0 \\0 & 0 & 0 & {B_{4} \times e^{j\; {{\theta 4}{(i)}}}}\end{pmatrix}\begin{pmatrix}Q_{1} & 0 & 0 & 0 \\0 & Q_{2} & 0 & 0 \\0 & 0 & Q_{3} & 0 \\0 & 0 & 0 & Q_{4}\end{pmatrix}\begin{pmatrix}a_{11} & a_{12} & a_{13} & a_{14} \\a_{21} & a_{22} & a_{23} & a_{24} \\a_{31} & a_{32} & a_{33} & a_{34} \\a_{41} & a_{42} & a_{43} & a_{44}\end{pmatrix}\begin{pmatrix}P_{1} & 0 & 0 & 0 \\0 & P_{2} & 0 & 0 \\0 & 0 & P_{3} & 0 \\0 & 0 & 0 & P_{4}\end{pmatrix}\begin{pmatrix}{s_{1}(i)} \\{s_{2}(i)} \\{s_{3}(i)} \\{s_{4}(i)}\end{pmatrix}}}\end{matrix} & {{Equation}\mspace{14mu} (61)}\end{matrix}$

FIG. 48 is a configuration diagram different from FIG. 47 in order toperform Equation (61). In FIG. 48, the component similar to that in FIG.47 is designated by the identical reference mark.

FIG. 48 differs from FIG. 47 in a positional relationship between thephase changing unit and power changing unit that are located at thesubsequent stage of weighting unit 4708. Accordingly, in FIG. 48, powerchanging unit 4710A exists at the subsequent stage of phase changingunit 4712A, power changing unit 4710B exists at the subsequent stage ofphase changing unit 4712B, power changing unit 4710C exists at thesubsequent stage of phase changing unit 4712C, and power changing unit4710D exists at the subsequent stage of phase changing unit 4712D.

Equation (62) holds because each component in FIG. 48 operates similarlyto each component in FIG. 47.

[Mathematical  formula  62] $\begin{matrix}\begin{matrix}{\begin{pmatrix}{z_{1}(i)} \\{z_{2}(i)} \\{z_{3}(i)} \\{z_{4}(i)}\end{pmatrix} = {\begin{pmatrix}Q_{1} & 0 & 0 & 0 \\0 & Q_{2} & 0 & 0 \\0 & 0 & Q_{3} & 0 \\0 & 0 & 0 & Q_{4}\end{pmatrix}\begin{pmatrix}{y_{1}(i)} & 0 & 0 & 0 \\0 & {y_{2}(i)} & 0 & 0 \\0 & 0 & {y_{3}(i)} & 0 \\0 & 0 & 0 & {y_{4}(i)}\end{pmatrix} \times F \times \begin{pmatrix}{P_{1} \times {s_{1}(i)}} \\{P_{2} \times {s_{2}(i)}} \\{P_{3} \times {s_{3}(i)}} \\{P_{4} \times {s_{4}(i)}}\end{pmatrix}}} \\{= {\begin{pmatrix}Q_{1} & 0 & 0 & 0 \\0 & Q_{2} & 0 & 0 \\0 & 0 & Q_{3} & 0 \\0 & 0 & 0 & Q_{4}\end{pmatrix}\begin{pmatrix}{y_{1}(i)} & 0 & 0 & 0 \\0 & {y_{2}(i)} & 0 & 0 \\0 & 0 & {y_{3}(i)} & 0 \\0 & 0 & 0 & {y_{4}(i)}\end{pmatrix}\begin{pmatrix}a_{11} & a_{12} & a_{13} & a_{14} \\a_{21} & a_{22} & a_{23} & a_{24} \\a_{31} & a_{32} & a_{33} & a_{34} \\a_{41} & a_{42} & a_{43} & a_{44}\end{pmatrix}\begin{pmatrix}{P_{1} \times {s_{1}(i)}} \\{P_{2} \times {s_{2}(i)}} \\{P_{3} \times {s_{3}(i)}} \\{P_{4} \times {s_{4}(i)}}\end{pmatrix}}} \\{= {\begin{pmatrix}Q_{1} & 0 & 0 & 0 \\0 & Q_{2} & 0 & 0 \\0 & 0 & Q_{3} & 0 \\0 & 0 & 0 & Q_{4}\end{pmatrix}\begin{pmatrix}{y_{1}(i)} & 0 & 0 & 0 \\0 & {y_{2}(i)} & 0 & 0 \\0 & 0 & {y_{3}(i)} & 0 \\0 & 0 & 0 & {y_{4}(i)}\end{pmatrix}\begin{pmatrix}a_{11} & a_{12} & a_{13} & a_{14} \\a_{21} & a_{22} & a_{23} & a_{24} \\a_{31} & a_{32} & a_{33} & a_{34} \\a_{41} & a_{42} & a_{43} & a_{44}\end{pmatrix}\begin{pmatrix}P_{1} & 0 & 0 & 0 \\0 & P_{2} & 0 & 0 \\0 & 0 & P_{3} & 0 \\0 & 0 & 0 & P_{4}\end{pmatrix}\begin{pmatrix}{s_{1}(i)} \\{s_{2}(i)} \\{s_{3}(i)} \\{s_{4}(i)}\end{pmatrix}}} \\{= {\begin{pmatrix}Q_{1} & 0 & 0 & 0 \\0 & Q_{2} & 0 & 0 \\0 & 0 & Q_{3} & 0 \\0 & 0 & 0 & Q_{4}\end{pmatrix}\begin{pmatrix}{B_{1} \times e^{j\; {{\theta 1}{(i)}}}} & 0 & 0 & 0 \\0 & {B_{2} \times e^{j\; {{\theta 2}{(i)}}}} & 0 & 0 \\0 & 0 & {B_{3} \times e^{j\; {{\theta 3}{(i)}}}} & 0 \\0 & 0 & 0 & {B_{4} \times e^{j\; {{\theta 4}{(i)}}}}\end{pmatrix}\begin{pmatrix}a_{11} & a_{12} & a_{13} & a_{14} \\a_{21} & a_{22} & a_{23} & a_{24} \\a_{31} & a_{32} & a_{33} & a_{34} \\a_{41} & a_{42} & a_{43} & a_{44}\end{pmatrix}\begin{pmatrix}P_{1} & 0 & 0 & 0 \\0 & P_{2} & 0 & 0 \\0 & 0 & P_{3} & 0 \\0 & 0 & 0 & P_{4}\end{pmatrix}\begin{pmatrix}{s_{1}(i)} \\{s_{2}(i)} \\{s_{3}(i)} \\{s_{4}(i)}\end{pmatrix}}}\end{matrix} & {{Equation}\mspace{14mu} (62)}\end{matrix}$

z₁(i) in Equation (61) is equal to z₁(i) in Equation (62), z₂(i) inEquation (61) is equal to z₂(i) in Equation (62), z₃(i) in Equation (61)is equal to z₃(i) in Equation (62), and z₄(i) in Equation (61) is equalto z₄(i) in Equation (62).

In FIGS. 47 and 48, post-power change values P₁, P₂, P₃, and P₄ andvalues Q₁, Q₂, Q₃, and Q₄ may be changed by the set of modulationschemes s₁(i), s₂(i), s₃(i), and s₄(i) (or need not be changed). ValuesP₁, P₂, P₃, and P₄ and/or values Q₁, Q₂, Q₃, and Q₄ may be changed bythe error correction coding method (such as the code length (blocklength) and the coding rate) (or need not be changed).

Similarly, in FIGS. 47 and 48, the phase changing method may be changedby the set of modulation schemes s₁(i), s₂(i), s₃(i), and s₄(i) (or neednot be changed). The phase changing method may be changed by the errorcorrection coding method (such as the code length (block length) and thecoding rate) (or need not be changed).

FIGS. 49, 50, 51, and 52 will be described below. FIGS. 49, 50, 51, and52 are views illustrating a configuration example in which the precodingmethod is performed when average power of the four transmission signalsvaries and when the phase changing unit is newly added.

In FIG. 49, the component operating similarly to FIG. 47 is designatedby the identical reference mark. FIG. 49 differs from FIG. 47 in thatphase changing units 4901A, 4901B, 4901C, and 4901D are added.

Phase changing unit 4901A receives baseband signal s₁(i) (4705A) andcontrol signal 4714 as input, and changes the phase of baseband signals₁(i) (4705A) based on control signal 4714. Accordingly, the post-phasechange signal of baseband signal s₁(i) (4705A) is expressed asC₁×e^(jω1(i))×s₁(i), and phase changing unit 4901A outputsC₁×e^(jω1(i))×s₁(i) as post-phase change signal 4902A (j may be animaginary unit, and C₁ may be 1.00 or a real number of 0 or more). Thevalue of the changed phase may be a function of i such as ω₁(i), or afixed value that is not the function of i.

Similarly, phase changing unit 4901B receives baseband signal s₂(i)(4705B) and control signal 4714 as input, and changes the phase ofbaseband signal s₂(i) (4705B) based on control signal 4714. Accordingly,the post-phase change signal of baseband signal s₂(i) (4705B) isexpressed as C₂×e^(jω2(i))×s₂(i), and phase changing unit 4901B outputsC₂×e^(jω2(i))×s₂(i) as post-phase change signal 4902B (j may be animaginary unit, and C₂ may be 1.00 or a real number of 0 or more). Thevalue of the changed phase may be a function of i such as ω₂(i), or afixed value that is not the function of i.

Similarly, phase changing unit 4901C receives baseband signal s₃(i)(4705C) and control signal 4714 as input, and changes the phase ofbaseband signal s₃(i) (4705C) based on control signal 4714. Accordingly,the post-phase change signal of baseband signal s₃(i) (4705C) isexpressed as C₃×e^(jω3(i))×s₃(i), and phase changing unit 4901C outputsC₃×e^(jω3(i))×s₃(i) as post-phase change signal 4902C (j may be animaginary unit, and C₃ may be 1.00 or a real number of 0 or more). Thevalue of the changed phase may be a function of i such as ω₃(i), or afixed value that is not the function of i.

Similarly, phase changing unit 4901D receives baseband signal s₄(i)(4705D) and control signal 4714 as input, and changes the phase ofbaseband signal s₄(i) (4705D) based on control signal 4714. Accordingly,the post-phase change signal of baseband signal s₄(i) (4705D) isexpressed as C₄×e^(jω4(i))×s₄(i), and phase changing unit 4901D outputsC₄×e^(jω4(i))×s₄(i) as post-phase change signal 4902D (j may be animaginary unit, and C₄ may be 1.00 or a real number of 0 or more). Thevalue of the changed phase may be a function of i such as ω₄(i), or afixed value that is not the function of i.

The components subsequent to phase changing units 4901A, 4901B, 4901C,and 4901D operate similarly to the components in FIG. 47. Accordingly,z₁(i), z₂(i), z₃(i), and z₄(i) that are of the outputs of phase changingunits 4712A, 4712B, 4712C, and 4712D in FIG. 49 are expressed byEquation (63).

[Mathematical  formula  63] $\begin{matrix}\begin{matrix}{\begin{pmatrix}{z_{1}(i)} \\{z_{2}(i)} \\{z_{3}(i)} \\{z_{4}(i)}\end{pmatrix} = {\begin{pmatrix}{y_{1}(i)} & 0 & 0 & 0 \\0 & {y_{2}(i)} & 0 & 0 \\0 & 0 & {y_{3}(i)} & 0 \\0 & 0 & 0 & {y_{4}(i)}\end{pmatrix}\begin{pmatrix}Q_{1} & 0 & 0 & 0 \\0 & Q_{2} & 0 & 0 \\0 & 0 & Q_{3} & 0 \\0 & 0 & 0 & Q_{4}\end{pmatrix}\begin{pmatrix}a_{11} & a_{12} & a_{13} & a_{14} \\a_{21} & a_{22} & a_{23} & a_{24} \\a_{31} & a_{32} & a_{33} & a_{34} \\a_{41} & a_{42} & a_{43} & a_{44}\end{pmatrix} \times}} \\{{\begin{pmatrix}P_{1} & 0 & 0 & 0 \\0 & P_{2} & 0 & 0 \\0 & 0 & P_{3} & 0 \\0 & 0 & 0 & P_{4}\end{pmatrix}\begin{pmatrix}{C_{1} \times e^{j\; {{\omega 1}{(i)}}}} & 0 & 0 & 0 \\0 & {C_{2} \times e^{j\; {{\omega 2}{(i)}}}} & 0 & 0 \\0 & 0 & {C_{3} \times e^{j\; {{\omega 3}{(i)}}}} & 0 \\0 & 0 & 0 & {C_{4} \times e^{j\; {{\omega 4}{(i)}}}}\end{pmatrix}\begin{pmatrix}{s_{1}(i)} \\{s_{2}(i)} \\{s_{3}(i)} \\{s_{4}(i)}\end{pmatrix}}} \\{= {\begin{pmatrix}{B_{1} \times e^{j\; {{\theta 1}{(i)}}}} & 0 & 0 & 0 \\0 & {B_{2} \times e^{j\; {{\theta 2}{(i)}}}} & 0 & 0 \\0 & 0 & {B_{3} \times e^{j\; {{\theta 3}{(i)}}}} & 0 \\0 & 0 & 0 & {B_{4} \times e^{j\; {{\theta 4}{(i)}}}}\end{pmatrix}\begin{pmatrix}Q_{1} & 0 & 0 & 0 \\0 & Q_{2} & 0 & 0 \\0 & 0 & Q_{3} & 0 \\0 & 0 & 0 & Q_{4}\end{pmatrix}\begin{pmatrix}a_{11} & a_{12} & a_{13} & a_{14} \\a_{21} & a_{22} & a_{23} & a_{24} \\a_{31} & a_{32} & a_{33} & a_{34} \\a_{41} & a_{42} & a_{43} & a_{44}\end{pmatrix} \times}} \\{{\begin{pmatrix}P_{1} & 0 & 0 & 0 \\0 & P_{2} & 0 & 0 \\0 & 0 & P_{3} & 0 \\0 & 0 & 0 & P_{4}\end{pmatrix}\begin{pmatrix}{C_{1} \times e^{j\; {{\omega 1}{(i)}}}} & 0 & 0 & 0 \\0 & {C_{2} \times e^{j\; {{\omega 2}{(i)}}}} & 0 & 0 \\0 & 0 & {C_{3} \times e^{j\; {{\omega 3}{(i)}}}} & 0 \\0 & 0 & 0 & {C_{4} \times e^{j\; {{\omega 4}{(i)}}}}\end{pmatrix}\begin{pmatrix}{s_{1}(i)} \\{s_{2}(i)} \\{s_{3}(i)} \\{s_{4}(i)}\end{pmatrix}}}\end{matrix} & {{Equation}\mspace{14mu} (63)}\end{matrix}$

FIG. 50 is a configuration diagram different from FIG. 49 in order toperform Equation (63). In FIG. 50, the component operating similarly tothat in FIG. 49 is designated by the identical reference mark.

FIG. 50 differs from FIG. 49 in a positional relationship between thephase changing unit and power changing unit that are located at thepreceding stage of weighting unit 4708. Accordingly, in FIG. 50, phasechanging unit 4901A exists at the subsequent stage of power changingunit 4706A, phase changing unit 4901B exists at the subsequent stage ofpower changing unit 4706B, phase changing unit 4901C exists at thesubsequent stage of power changing unit 4706C, and phase changing unit4901D exists at the subsequent stage of power changing unit 4706D.

Equation (64) holds because each component in FIG. 50 operates similarlyto each component in FIG. 49.

[Mathematical  formula  64] $\begin{matrix}\begin{matrix}{\begin{pmatrix}{z_{1}(i)} \\{z_{2}(i)} \\{z_{3}(i)} \\{z_{4}(i)}\end{pmatrix} = {\begin{pmatrix}Q_{1} & 0 & 0 & 0 \\0 & Q_{2} & 0 & 0 \\0 & 0 & Q_{3} & 0 \\0 & 0 & 0 & Q_{4}\end{pmatrix}\begin{pmatrix}{y_{1}(i)} & 0 & 0 & 0 \\0 & {y_{2}(i)} & 0 & 0 \\0 & 0 & {y_{3}(i)} & 0 \\0 & 0 & 0 & {y_{4}(i)}\end{pmatrix}\begin{pmatrix}a_{11} & a_{12} & a_{13} & a_{14} \\a_{21} & a_{22} & a_{23} & a_{24} \\a_{31} & a_{32} & a_{33} & a_{34} \\a_{41} & a_{42} & a_{43} & a_{44}\end{pmatrix} \times}} \\{{\begin{pmatrix}P_{1} & 0 & 0 & 0 \\0 & P_{2} & 0 & 0 \\0 & 0 & P_{3} & 0 \\0 & 0 & 0 & P_{4}\end{pmatrix}\begin{pmatrix}{C_{1} \times e^{j\; {{\omega 1}{(i)}}}} & 0 & 0 & 0 \\0 & {C_{2} \times e^{j\; {{\omega 2}{(i)}}}} & 0 & 0 \\0 & 0 & {C_{3} \times e^{j\; {{\omega 3}{(i)}}}} & 0 \\0 & 0 & 0 & {C_{4} \times e^{j\; {{\omega 4}{(i)}}}}\end{pmatrix}\begin{pmatrix}{s_{1}(i)} \\{s_{2}(i)} \\{s_{3}(i)} \\{s_{4}(i)}\end{pmatrix}}} \\{= {\begin{pmatrix}Q_{1} & 0 & 0 & 0 \\0 & Q_{2} & 0 & 0 \\0 & 0 & Q_{3} & 0 \\0 & 0 & 0 & Q_{4}\end{pmatrix}\begin{pmatrix}{B_{1} \times e^{j\; {{\theta 1}{(i)}}}} & 0 & 0 & 0 \\0 & {B_{2} \times e^{j\; {{\theta 2}{(i)}}}} & 0 & 0 \\0 & 0 & {B_{3} \times e^{j\; {{\theta 3}{(i)}}}} & 0 \\0 & 0 & 0 & {B_{4} \times e^{j\; {{\theta 4}{(i)}}}}\end{pmatrix}\begin{pmatrix}a_{11} & a_{12} & a_{13} & a_{14} \\a_{21} & a_{22} & a_{23} & a_{24} \\a_{31} & a_{32} & a_{33} & a_{34} \\a_{41} & a_{42} & a_{43} & a_{44}\end{pmatrix} \times}} \\{{\begin{pmatrix}P_{1} & 0 & 0 & 0 \\0 & P_{2} & 0 & 0 \\0 & 0 & P_{3} & 0 \\0 & 0 & 0 & P_{4}\end{pmatrix}\begin{pmatrix}{C_{1} \times e^{j\; {{\omega 1}{(i)}}}} & 0 & 0 & 0 \\0 & {C_{2} \times e^{j\; {{\omega 2}{(i)}}}} & 0 & 0 \\0 & 0 & {C_{3} \times e^{j\; {{\omega 3}{(i)}}}} & 0 \\0 & 0 & 0 & {C_{4} \times e^{j\; {{\omega 4}{(i)}}}}\end{pmatrix}\begin{pmatrix}{s_{1}(i)} \\{s_{2}(i)} \\{s_{3}(i)} \\{s_{4}(i)}\end{pmatrix}}}\end{matrix} & {{Equation}\mspace{14mu} (64)}\end{matrix}$

z₁(i) in Equation (63) is equal to z₁(i) in Equation (64), z₂(i) inEquation (63) is equal to z₂(i) in Equation (64), z₃(i) in Equation (63)is equal to z₃(i) in Equation (64), and z₄(i) in Equation (63) is equalto z₄(i) in Equation (64).

In FIGS. 49 and 50, post-power change values P₁, P₂, P₃, and P₄ andvalues Q₁, Q₂, Q₃, and Q₄ may be changed by the set of modulationschemes s₁(i), s₂(i), s₃(i), and s₄(i) (or need not be changed). ValuesP₁, P₂, P₃, and P₄ and/or values Q₁, Q₂, Q₃, and Q₄ may be changed bythe error correction coding method (such as the code length (blocklength) and the coding rate) (or need not be changed).

Similarly, in FIGS. 49 and 50, the phase changing method for both thepreceding and subsequent stages of weighting unit 4708 may be changed bythe set of modulation schemes s₁(i), s₂(i), s₃(i), and s₄(i) (or neednot be changed). The phase changing method may be changed by the errorcorrection coding method (such as the code length (block length) and thecoding rate) (or need not be changed).

In FIG. 51, the component operating similarly to that in FIG. 48 isdesignated by the identical reference mark. FIG. 51 differs from FIG. 48in that phase changing units 4901A, 4901B, 4901C, and 4901D are added.

Phase changing unit 4901A receives baseband signal s₁(i) (4705A) andcontrol signal 4714 as input, and changes the phase of baseband signals₁(i) (4705A) based on control signal 4714. Accordingly, the post-phasechange signal of baseband signal s₁(i) (4705A) is expressed asC₁×e^(jω1(i))×s₁(i), and phase changing unit 4901A outputsC₁×e^(jω1(i))×s₁(i) as post-phase change signal 4902A (j may be animaginary unit, and C₁ may be 1.00 or a real number of 0 or more). Thevalue of the changed phase may be a function of i such as ω₁(i), or afixed value that is not the function of i.

Similarly, phase changing unit 4901B receives baseband signal s₂(i)(4705B) and control signal 4714 as input, and changes the phase ofbaseband signal s₂(i) (4705B) based on control signal 4714. Accordingly,the post-phase change signal of baseband signal s₂(i) (4705B) isexpressed as C₂×e^(jω2(i))×s₂(i), and phase changing unit 4901B outputsC₂×e^(jω2(i))×s₂(i) as post-phase change signal 4902B (j may be animaginary unit, and C₂ may be 1.00 or a real number of 0 or more). Thevalue of the changed phase may be a function of i such as ω₂(i), or afixed value that is not the function of i.

Similarly, phase changing unit 4901C receives baseband signal s₃(i)(4705C) and control signal 4714 as input, and changes the phase ofbaseband signal s₃(i) (4705C) based on control signal 4714. Accordingly,the post-phase change signal of baseband signal s₃(i) (4705C) isexpressed as C₃×e^(jω3(i))×s₃(i), and phase changing unit 4901C outputsC₃×e^(jω3(i))×s₃(i) as post-phase change signal 4902C (j may be animaginary unit, and C₃ may be 1.00 or a real number of 0 or more). Thevalue of the changed phase may be a function of i such as ω₃(i), or afixed value that is not the function of i.

Similarly, phase changing unit 4901D receives baseband signal s₄(i)(4705D) and control signal 4714 as input, and changes the phase ofbaseband signal s₄(i) (4705D) based on control signal 4714. Accordingly,the post-phase change signal of baseband signal s₄(i) (4705D) isexpressed as C₄×e^(jω4(i))×s₄(i), and phase changing unit 4901D outputsC₄×e^(jω4(i))×s₄(i) as post-phase change signal 4902D (j may be animaginary unit, and C₄ may be 1.00 or a real number of 0 or more). Thevalue of the changed phase may be a function of i such as ω₄(i), or afixed value that is not the function of i.

The components subsequent to phase changing units 4901A, 4901B, 4901C,and 4901D operate similarly to the components in FIG. 48. Accordingly,z₁(i), z₂(i), z₃(i), and z₄(i) that are of the outputs of phase changingunits 4712A, 4712B, 4712C, and 4712D in FIG. 51 are expressed byEquation (65).

[Mathematical  formula  65] $\begin{matrix}\begin{matrix}{\begin{pmatrix}{z_{1}(i)} \\{z_{2}(i)} \\{z_{3}(i)} \\{z_{4}(i)}\end{pmatrix} = {\begin{pmatrix}{y_{1}(i)} & 0 & 0 & 0 \\0 & {y_{2}(i)} & 0 & 0 \\0 & 0 & {y_{3}(i)} & 0 \\0 & 0 & 0 & {y_{4}(i)}\end{pmatrix}\begin{pmatrix}Q_{1} & 0 & 0 & 0 \\0 & Q_{2} & 0 & 0 \\0 & 0 & Q_{3} & 0 \\0 & 0 & 0 & Q_{4}\end{pmatrix}\begin{pmatrix}a_{11} & a_{12} & a_{13} & a_{14} \\a_{21} & a_{22} & a_{23} & a_{24} \\a_{31} & a_{32} & a_{33} & a_{34} \\a_{41} & a_{42} & a_{43} & a_{44}\end{pmatrix} \times}} \\{{\begin{pmatrix}{C_{1} \times e^{j\; {{\omega 1}{(i)}}}} & 0 & 0 & 0 \\0 & {C_{2} \times e^{j\; {{\omega 2}{(i)}}}} & 0 & 0 \\0 & 0 & {C_{3} \times e^{j\; {{\omega 3}{(i)}}}} & 0 \\0 & 0 & 0 & {C_{4} \times e^{j\; {{\omega 4}{(i)}}}}\end{pmatrix}\begin{pmatrix}P_{1} & 0 & 0 & 0 \\0 & P_{2} & 0 & 0 \\0 & 0 & P_{3} & 0 \\0 & 0 & 0 & P_{4}\end{pmatrix}\begin{pmatrix}{s_{1}(i)} \\{s_{2}(i)} \\{s_{3}(i)} \\{s_{4}(i)}\end{pmatrix}}} \\{= {\begin{pmatrix}{B_{1} \times e^{j\; {{\theta 1}{(i)}}}} & 0 & 0 & 0 \\0 & {B_{2} \times e^{j\; {{\theta 2}{(i)}}}} & 0 & 0 \\0 & 0 & {B_{3} \times e^{j\; {{\theta 3}{(i)}}}} & 0 \\0 & 0 & 0 & {B_{4} \times e^{j\; {{\theta 4}{(i)}}}}\end{pmatrix}\begin{pmatrix}Q_{1} & 0 & 0 & 0 \\0 & Q_{2} & 0 & 0 \\0 & 0 & Q_{3} & 0 \\0 & 0 & 0 & Q_{4}\end{pmatrix}\begin{pmatrix}a_{11} & a_{12} & a_{13} & a_{14} \\a_{21} & a_{22} & a_{23} & a_{24} \\a_{31} & a_{32} & a_{33} & a_{34} \\a_{41} & a_{42} & a_{43} & a_{44}\end{pmatrix} \times}} \\{{\begin{pmatrix}{C_{1} \times e^{j\; {{\omega 1}{(i)}}}} & 0 & 0 & 0 \\0 & {C_{2} \times e^{j\; {{\omega 2}{(i)}}}} & 0 & 0 \\0 & 0 & {C_{3} \times e^{j\; {{\omega 3}{(i)}}}} & 0 \\0 & 0 & 0 & {C_{4} \times e^{j\; {{\omega 4}{(i)}}}}\end{pmatrix}\begin{pmatrix}P_{1} & 0 & 0 & 0 \\0 & P_{2} & 0 & 0 \\0 & 0 & P_{3} & 0 \\0 & 0 & 0 & P_{4}\end{pmatrix}\begin{pmatrix}{s_{1}(i)} \\{s_{2}(i)} \\{s_{3}(i)} \\{s_{4}(i)}\end{pmatrix}}}\end{matrix} & {{Equation}\mspace{14mu} (65)}\end{matrix}$

FIG. 52 is a configuration diagram different from FIG. 51 in order toperform Equation (65). In FIG. 52, the component operating similarly tothat in FIG. 51 is designated by the identical reference mark.

FIG. 52 differs from FIG. 51 in a positional relationship between thephase changing unit and power changing unit that are located at thepreceding stage of weighting unit 4708. Accordingly, in FIG. 52, phasechanging unit 4901A exists at the subsequent stage of power changingunit 4706A, phase changing unit 4901B exists at the subsequent stage ofpower changing unit 4706B, phase changing unit 4901C exists at thesubsequent stage of power changing unit 4706C, and phase changing unit4901D exists at the subsequent stage of power changing unit 4706D.

Equation (66) holds because each component in FIG. 52 operates similarlyto each component in FIG. 51.

[Mathematical  formula  66] $\begin{matrix}\begin{matrix}{\begin{pmatrix}{z_{1}(i)} \\{z_{2}(i)} \\{z_{3}(i)} \\{z_{4}(i)}\end{pmatrix} = {\begin{pmatrix}Q_{1} & 0 & 0 & 0 \\0 & Q_{2} & 0 & 0 \\0 & 0 & Q_{3} & 0 \\0 & 0 & 0 & Q_{4}\end{pmatrix}\begin{pmatrix}{y_{1}(i)} & 0 & 0 & 0 \\0 & {y_{2}(i)} & 0 & 0 \\0 & 0 & {y_{3}(i)} & 0 \\0 & 0 & 0 & {y_{4}(i)}\end{pmatrix}\begin{pmatrix}a_{11} & a_{12} & a_{13} & a_{14} \\a_{21} & a_{22} & a_{23} & a_{24} \\a_{31} & a_{32} & a_{33} & a_{34} \\a_{41} & a_{42} & a_{43} & a_{44}\end{pmatrix} \times}} \\{{\begin{pmatrix}{C_{1} \times e^{j\; {{\omega 1}{(i)}}}} & 0 & 0 & 0 \\0 & {C_{2} \times e^{j\; {{\omega 2}{(i)}}}} & 0 & 0 \\0 & 0 & {C_{3} \times e^{j\; {{\omega 3}{(i)}}}} & 0 \\0 & 0 & 0 & {C_{4} \times e^{j\; {{\omega 4}{(i)}}}}\end{pmatrix}\begin{pmatrix}P_{1} & 0 & 0 & 0 \\0 & P_{2} & 0 & 0 \\0 & 0 & P_{3} & 0 \\0 & 0 & 0 & P_{4}\end{pmatrix}\begin{pmatrix}{s_{1}(i)} \\{s_{2}(i)} \\{s_{3}(i)} \\{s_{4}(i)}\end{pmatrix}}} \\{= {\begin{pmatrix}Q_{1} & 0 & 0 & 0 \\0 & Q_{2} & 0 & 0 \\0 & 0 & Q_{3} & 0 \\0 & 0 & 0 & Q_{4}\end{pmatrix}\begin{pmatrix}{B_{1} \times e^{j\; {{\theta 1}{(i)}}}} & 0 & 0 & 0 \\0 & {B_{2} \times e^{j\; {{\theta 2}{(i)}}}} & 0 & 0 \\0 & 0 & {B_{3} \times e^{j\; {{\theta 3}{(i)}}}} & 0 \\0 & 0 & 0 & {B_{4} \times e^{j\; {{\theta 4}{(i)}}}}\end{pmatrix}\begin{pmatrix}a_{11} & a_{12} & a_{13} & a_{14} \\a_{21} & a_{22} & a_{23} & a_{24} \\a_{31} & a_{32} & a_{33} & a_{34} \\a_{41} & a_{42} & a_{43} & a_{44}\end{pmatrix} \times}} \\{{\begin{pmatrix}{C_{1} \times e^{j\; {{\omega 1}{(i)}}}} & 0 & 0 & 0 \\0 & {C_{2} \times e^{j\; {{\omega 2}{(i)}}}} & 0 & 0 \\0 & 0 & {C_{3} \times e^{j\; {{\omega 3}{(i)}}}} & 0 \\0 & 0 & 0 & {C_{4} \times e^{j\; {{\omega 4}{(i)}}}}\end{pmatrix}\begin{pmatrix}P_{1} & 0 & 0 & 0 \\0 & P_{2} & 0 & 0 \\0 & 0 & P_{3} & 0 \\0 & 0 & 0 & P_{4}\end{pmatrix}\begin{pmatrix}{s_{1}(i)} \\{s_{2}(i)} \\{s_{3}(i)} \\{s_{4}(i)}\end{pmatrix}}}\end{matrix} & {{Equation}\mspace{14mu} (66)}\end{matrix}$

z₁(i) in Equation (63), z₁(i) in Equation (64), z₁(i) in Equation (65),and z₁(i) in Equation (66) are equal to one another, z₂(i) in Equation(63), z₂(i) in Equation (64), z₂(i) in Equation (65), and z₂(i) inEquation (66) are equal to one another, z₃(i) in Equation (63), z₃(i) inEquation (64), z₃(i) in Equation (65), and z₃(i) in Equation (66) areequal to one another, and z₄(i) in Equation (63), z₄(i) in Equation(64), z₄(i) in Equation (65), and z₄(i) in Equation (66) are equal toone another.

In FIGS. 51 and 52, post-power change values P₁, P₂, P₃, and P₄ andvalues Q₁, Q₂, Q₃, and Q₄ may be changed by the set of modulationschemes s₁(i), s₂(i), s₃(i), and s₄(i) (or need not be changed). ValuesP₁, P₂, P₃, and P₄ and/or values Q₁, Q₂, Q₃, and Q₄ may be changed bythe error correction coding method (such as the code length (blocklength) and the coding rate) (or need not be changed).

Similarly, in FIGS. 51 and 52, the phase changing method may be changedby the set of modulation schemes s₁(i), s₂(i), s₃(i), and s₄(i) (or neednot be changed). The phase changing method may be changed by the errorcorrection coding method (such as the code length (block length) and thecoding rate) (or need not be changed).

Accordingly, the present exemplary embodiment leads to the followingadvantageous effect. That is, there is a high possibility of improvingthe data reception quality, and particularly there is a high possibilityof largely improving the data reception quality in the LOS environmentin which the direct wave is dominant.

For example, the precoding matrix may be switched when the set ofmodulation schemes of the four streams is switched. The phase changingmethod may be switched when the set of modulation schemes of the fourstreams is switched. The precoding matrix and the phase changing methodmay be switched when the set of modulation schemes of the four streamsis switched (the precoding matrix and the phase changing need not beswitched even if the set of modulation schemes of the four streams isswitched).

Fourth Exemplary Embodiment

In the first and second exemplary embodiments, as illustrated in FIGS.5, 6, 19, 20, 27, 28, 39, and 40, the mapping, the weighting, and thephase change are sequentially performed by way of example. Amodification in which a phase changing unit or a power changing unit isadded to the first and second exemplary embodiments will be described ina fourth exemplary embodiment. The phase changing method performed at asubsequent stage of the weighting may be operated similarly to the firstand second exemplary embodiments.

The case that the three streams are transmitted using the three antennasare described in the fourth exemplary embodiment. In FIGS. 5, 6, 19, and20, mapping unit 506A to phase changing unit 517A, mapping unit 506B tophase changing unit 517B, and mapping unit 506C to phase changing unit517C may be replaced with those in FIGS. 53, 54, 55, 56, 57, and 58. Theoperation in each drawings will be described below.

FIGS. 53 and 54 are views illustrating a configuration example in whichthe precoding method is performed when average transmission power of thethree transmission signals varies.

In FIG. 53, mapping unit 4704 receives data 4703 and control signal 4714as input. It is assumed that control signal 4714 assigns thetransmission of the three streams as the transmission method.Additionally, it is assumed that control signal 4714 assigns modulationschemes α, β, and γ as the modulation schemes of the three streams.Modulation scheme α modulates p-bit data, modulation scheme β modulatesq-bit data, and modulation scheme γ modulates r-bit data. (For example,the modulation scheme modulates 4-bit data for the 16QAM, and themodulation scheme modulates 6-bit data for the 64QAM.)

Therefore, mapping unit 4704 modulates the p-bit data in (p+q+r)-bitdata using modulation scheme α, and generates and outputs basebandsignal s₁(t) (4705A). Mapping unit 4704 modulates the q-bit data usingmodulation scheme β, and outputs baseband signal s₂(t) (4705B). Mappingunit 4704 modulates the r-bit data using modulation scheme γ, andoutputs baseband signal s₃(t) (4705C).

In FIG. 53, the one mapping unit is described. Alternatively, a mappingunit generating s₁(t) and a mapping unit generating s₂(t) may existseparately. At this point, coded data 4703 is divided into the mappingunit generating s₁(t), the mapping unit generating s₂(t), and themapping unit generating s₃(t). For example, as illustrated in FIG. 53,mapping unit 4704 receives pieces of data 4703, 4703B, and 4703C asinput, performs the mapping on data 4703, and generates and outputsbaseband signal s₁(t) (4705A). Mapping unit 4704 also performs themapping on data 4703B, and generates and outputs baseband signal s₂(t)(4705B). Mapping unit 4704 also performs the mapping on data 4703C, andgenerates and outputs baseband signal s₃(t) (4705C).

Baseband signals s₁(t), s₂(t), and s₃(t) are expressed by complexnumbers (however, may be either complex numbers or real numbers), and tis a time. For the use of the transmission method in which themulti-carrier such as OFDM (Orthogonal Frequency Division Multiplexing)is used, Si, s₂, and s₃ are functions of frequency f such as s₁(f),s₂(f), and s₃(f) or functions of time t and frequency f such as s₁(t,f), s₂(t, f), and s₃(t, f).

Hereinafter, the baseband signal, the precoding matrix, and the phasechanging are described as the function of time t. Alternatively, thebaseband signal, the precoding matrix, and the phase changing may beconsidered as the function of frequency f, and the function of time tand frequency f.

Sometimes the baseband signal, the precoding matrix, and the phasechanging are described as the function of symbol number i. In this case,the baseband signal, the precoding matrix, and the phase changing may beconsidered as the function of time t, the function of frequency f, orthe function of time t and frequency f. That is, the symbol and thebaseband signal may be generated and disposed on the time axis directionand the frequency axis direction. The symbol and the baseband signal mayalso be generated and disposed on the time axis direction and thefrequency axis direction.

Power changing unit 4706A (power adjuster 4706A) receives basebandsignal s₁(t) (4705A) and control signal 4714 as input, sets real numberP₁ based on control signal 4714, and outputs P₁×s₁(t) as post-powerchange signal 4707A. (Although P₁ is a real number, P₁ may be a complexnumber.)

Similarly, power changing unit 4706B (power adjuster 4706B) receivesbaseband signal s₂(t) (4705B) and control signal 4714 as input, setsreal number P₂, and outputs P₂×s₂(t) as post-power change signal 4707B.(Although P₂ is a real number, P₂ may be a complex number.)

Similarly, power changing unit 4706C (power adjuster 4706C) receivesbaseband signal s₃(t) (4705C) and control signal 4714 as input, setsreal number P₃, and outputs P₃×s₃(t) as post-power change signal 4707C.(Although P₃ is a real number, P₃ may be a complex number.)

Weighting unit 4708 receives post-power change signals 4707A, 4707B, and4707C and control signal 4714 as input, and sets precoding matrix F (orF(i)) based on control signal 4714. Assuming that i is a slot number(symbol number), weighting unit 4708 calculates Equation (67).

[Mathematical  formula  67] $\begin{matrix}\begin{matrix}{\begin{pmatrix}{u_{1}(i)} \\{u_{2}(i)} \\{u_{3}(i)}\end{pmatrix} = {F \times \begin{pmatrix}{P_{1} \times {s_{1}(i)}} \\{P_{2} \times {s_{2}(i)}} \\{P_{3} \times {s_{3}(i)}}\end{pmatrix}}} \\{= {\begin{pmatrix}a_{11} & a_{12} & a_{13} \\a_{21} & a_{22} & a_{23} \\a_{31} & a_{32} & a_{33}\end{pmatrix}\begin{pmatrix}{P_{1} \times {s_{1}(i)}} \\{P_{2} \times {s_{2}(i)}} \\{P_{3} \times {s_{3}(i)}}\end{pmatrix}}} \\{= {\begin{pmatrix}a_{11} & a_{12} & a_{13} \\a_{21} & a_{22} & a_{23} \\a_{31} & a_{32} & a_{33}\end{pmatrix}\begin{pmatrix}P_{1} & 0 & 0 \\0 & P_{2} & 0 \\0 & 0 & P_{3}\end{pmatrix}\begin{pmatrix}{s_{1}(i)} \\{s_{2}(i)} \\{s_{3}(i)}\end{pmatrix}}}\end{matrix} & {{Equation}\mspace{14mu} (67)}\end{matrix}$

Precoding matrix F is already described above using Equations (37) and(38) of the first exemplary embodiment. Precoding matrix may be afunction of i, or need not be a function of i. When precoding matrix isthe function of i, precoding matrix F is switched by the slot number(symbol number).

Weighting unit 4708 outputs u₁(i) in Equation (67) as weighted signal4709A, outputs u₂(i) in Equation (67) as weighted signal 4709B, andoutputs u₃(i) in Equation (67) as weighted signal 4709C.

Power changing unit 4710A receives weighted signal 4709A (u₁(i)) andcontrol signal 4714 as input, sets real number Q₁ based on controlsignal 4714, and outputs Q₁×u₁(i) as post-power change signal 4711A.(Although Q₁ is a real number, Q₁ may be a complex number.)

Similarly, power changing unit 4710B receives weighted signal 4709B(u₂(i)) and control signal 4714 as input, sets real number Q₂ based oncontrol signal 4714, and outputs Q₂×u₂(i) as post-power change signal4711B. (Although Q₂ is a real number, Q₂ may be a complex number.)

Similarly, power changing unit 4710C receives weighted signal 4709C(u₃(i)) and control signal 4714 as input, sets real number Q₃ based oncontrol signal 4714, and outputs Q₃×u₃(i) as post-power change signal4711C. (Although Q₃ is a real number, Q₃ may be a complex number.)

Phase changing unit 4712A receives post-power change signal 4711A ofQ₁×u₁(i) and control signal 4714 as input, and changes the phase ofpost-power change signal 4711A of Q₁×u_(i)(i) based on control signal4714. Accordingly, the signal in which the phase of post-power changesignal 4711A of Q₁×u₁(i) is changed is expressed asB₁×e^(jθ1(i))×Q₁×u₁(i), and phase changing unit 4712A outputsB₁×e^(jθ1(i))×Q₁×u₁(i) as post-phase change signal 4713A (j may be animaginary unit, and B₁ may be 1.00 or a real number of 0 or more). Oneof the features of the third exemplary embodiment is that the value ofthe changed phase is a function of i such as θ₁(i). The method forproviding θ₁(i) is already described above in the first exemplaryembodiment.

Phase changing unit 4712B receives post-power change signal 4711B ofQ₂×u₂(i) and control signal 4714 as input, and changes the phase ofpost-power change signal 4711B of Q₂×u₂(i) based on control signal 4714.Accordingly, the signal in which the phase of post-power change signal4711B of Q₂×u₂(i) is changed is expressed as B₂×e^(jθ2(i))X Q₂×u₂(i),and phase changing unit 4712B outputs B₂×e^(jθ2(i))×Q₂×u₂(i) aspost-phase change signal 4713B (j may be an imaginary unit, and B₂ maybe 1.00 or a real number of 0 or more). One of the features of the thirdexemplary embodiment is that the value of the changed phase is afunction of i such as θ₂(i). The method for providing θ₂(i) is alreadydescribed above in the first exemplary embodiment.

Phase changing unit 4712C receives post-power change signal 4711C ofQ₃×u₃(i) and control signal 4714 as input, and changes the phase ofpost-power change signal 4711C of Q₃×u₃(i) based on control signal 4714.Accordingly, the signal in which the phase of post-power change signal4711C of Q₃×u₃(i) is changed is expressed as B₃×e^(jθ3(i))×Q₃×u₃(i), andphase changing unit 4712C outputs B₃×e^(jθ3(i))×Q₃×u₃(i) as post-phasechange signal 4713C (j may be an imaginary unit, and B₃ may be 1.00 or areal number of 0 or more). One of the features of the third exemplaryembodiment is that the value of the changed phase is a function of isuch as θ₃(i). The method for providing θ₃(i) is already described abovein the first exemplary embodiment.

Therefore, Equation (68) holds.

[Mathematical  formula  68] $\begin{matrix}\begin{matrix}{\begin{pmatrix}{z_{1}(i)} \\{z_{2}(i)} \\{z_{3}(i)}\end{pmatrix} = {\begin{pmatrix}{y_{1}(i)} & 0 & 0 \\0 & {y_{2}(i)} & 0 \\0 & 0 & {y_{3}(i)}\end{pmatrix}\begin{pmatrix}Q_{1} & 0 & 0 \\0 & Q_{2} & 0 \\0 & 0 & Q_{3}\end{pmatrix} \times F \times \begin{pmatrix}{P_{1} \times {s_{1}(i)}} \\{P_{2} \times {s_{2}(i)}} \\{P_{3} \times {s_{3}(i)}}\end{pmatrix}}} \\{= {\begin{pmatrix}{y_{1}(i)} & 0 & 0 \\0 & {y_{2}(i)} & 0 \\0 & 0 & {y_{3}(i)}\end{pmatrix}\begin{pmatrix}Q_{1} & 0 & 0 \\0 & Q_{2} & 0 \\0 & 0 & Q_{3}\end{pmatrix}\begin{pmatrix}a_{11} & a_{12} & a_{13} \\a_{21} & a_{22} & a_{23} \\a_{31} & a_{32} & a_{33}\end{pmatrix}\begin{pmatrix}{P_{1} \times {s_{1}(i)}} \\{P_{2} \times {s_{2}(i)}} \\{P_{3} \times {s_{3}(i)}}\end{pmatrix}}} \\{= {\begin{pmatrix}{y_{1}(i)} & 0 & 0 \\0 & {y_{2}(i)} & 0 \\0 & 0 & {y_{3}(i)}\end{pmatrix}\begin{pmatrix}Q_{1} & 0 & 0 \\0 & Q_{2} & 0 \\0 & 0 & Q_{3}\end{pmatrix}\begin{pmatrix}a_{11} & a_{12} & a_{13} \\a_{21} & a_{22} & a_{23} \\a_{31} & a_{32} & a_{33}\end{pmatrix}\begin{pmatrix}P_{1} & 0 & 0 \\0 & P_{2} & 0 \\0 & 0 & P_{3}\end{pmatrix}\begin{pmatrix}{s_{1}(i)} \\{s_{2}(i)} \\{s_{3}(i)}\end{pmatrix}}} \\{= {\begin{pmatrix}{B_{1} \times e^{j\; {{\theta 1}{(i)}}}} & 0 & 0 \\0 & {B_{2} \times e^{j\; {{\theta 2}{(i)}}}} & 0 \\0 & 0 & {B_{3} \times e^{j\; {{\theta 3}{(i)}}}}\end{pmatrix}\begin{pmatrix}Q_{1} & 0 & 0 \\0 & Q_{2} & 0 \\0 & 0 & Q_{3}\end{pmatrix}\begin{pmatrix}a_{11} & a_{12} & a_{13} \\a_{21} & a_{22} & a_{23} \\a_{31} & a_{32} & a_{33}\end{pmatrix}\begin{pmatrix}P_{1} & 0 & 0 \\0 & P_{2} & 0 \\0 & 0 & P_{3}\end{pmatrix}\begin{pmatrix}{s_{1}(i)} \\{s_{2}(i)} \\{s_{3}(i)}\end{pmatrix}}}\end{matrix} & {{Equation}\mspace{14mu} (68)}\end{matrix}$

FIG. 54 is a configuration diagram different from FIG. 53 in order toperform Equation (68). In FIG. 54, the component operating similarly tothat in FIG. 53 is designated by the identical reference mark.

FIG. 54 differs from FIG. 53 in a positional relationship between thephase changing unit and power changing unit that are located at thesubsequent stage of weighting unit 4708. Accordingly, in FIG. 54, powerchanging unit 4710A exists at the subsequent stage of phase changingunit 4712A, power changing unit 4710B exists at the subsequent stage ofphase changing unit 4712B, and power changing unit 4710C exists at thesubsequent stage of phase changing unit 4712C.

Equation (69) holds because each component in FIG. 54 operates similarlyto each component in FIG. 53.

[Mathematical  formula  69] $\begin{matrix}\begin{matrix}{\begin{pmatrix}{z_{1}(i)} \\{z_{2}(i)} \\{z_{3}(i)}\end{pmatrix} = {\begin{pmatrix}Q_{1} & 0 & 0 \\0 & Q_{2} & 0 \\0 & 0 & Q_{3}\end{pmatrix}\begin{pmatrix}{y_{1}(i)} & 0 & 0 \\0 & {y_{2}(i)} & 0 \\0 & 0 & {y_{3}(i)}\end{pmatrix} \times F \times \begin{pmatrix}{P_{1} \times {s_{1}(i)}} \\{P_{2} \times {s_{2}(i)}} \\{P_{3} \times {s_{3}(i)}}\end{pmatrix}}} \\{= {\begin{pmatrix}Q_{1} & 0 & 0 \\0 & Q_{2} & 0 \\0 & 0 & Q_{3}\end{pmatrix}\begin{pmatrix}{y_{1}(i)} & 0 & 0 \\0 & {y_{2}(i)} & 0 \\0 & 0 & {y_{3}(i)}\end{pmatrix}\begin{pmatrix}a_{11} & a_{12} & a_{13} \\a_{21} & a_{22} & a_{23} \\a_{31} & a_{32} & a_{33}\end{pmatrix}\begin{pmatrix}{P_{1} \times {s_{1}(i)}} \\{P_{2} \times {s_{2}(i)}} \\{P_{3} \times {s_{3}(i)}}\end{pmatrix}}} \\{= {\begin{pmatrix}Q_{1} & 0 & 0 \\0 & Q_{2} & 0 \\0 & 0 & Q_{3}\end{pmatrix}\begin{pmatrix}{y_{1}(i)} & 0 & 0 \\0 & {y_{2}(i)} & 0 \\0 & 0 & {y_{3}(i)}\end{pmatrix}\begin{pmatrix}a_{11} & a_{12} & a_{13} \\a_{21} & a_{22} & a_{23} \\a_{31} & a_{32} & a_{33}\end{pmatrix}\begin{pmatrix}P_{1} & 0 & 0 \\0 & P_{2} & 0 \\0 & 0 & P_{3}\end{pmatrix}\begin{pmatrix}{s_{1}(i)} \\{s_{2}(i)} \\{s_{3}(i)}\end{pmatrix}}} \\{= {\begin{pmatrix}Q_{1} & 0 & 0 \\0 & Q_{2} & 0 \\0 & 0 & Q_{3}\end{pmatrix}\begin{pmatrix}{B_{1} \times e^{j\; {{\theta 1}{(i)}}}} & 0 & 0 \\0 & {B_{2} \times e^{j\; {{\theta 2}{(i)}}}} & 0 \\0 & 0 & {B_{3} \times e^{j\; {{\theta 3}{(i)}}}}\end{pmatrix}\begin{pmatrix}a_{11} & a_{12} & a_{13} \\a_{21} & a_{22} & a_{23} \\a_{31} & a_{32} & a_{33}\end{pmatrix}\begin{pmatrix}P_{1} & 0 & 0 \\0 & P_{2} & 0 \\0 & 0 & P_{3}\end{pmatrix}\begin{pmatrix}{s_{1}(i)} \\{s_{2}(i)} \\{s_{3}(i)}\end{pmatrix}}}\end{matrix} & {{Equation}\mspace{14mu} (69)}\end{matrix}$

z₁(i) in Equation (68) is equal to z₁(i) in Equation (69), z₂(i) inEquation (68) is equal to z₂(i) in Equation (69), and z₃(i) in Equation(68) is equal to z₃(i) in Equation (69).

In FIGS. 53 and 54, post-power change values P₁, P₂, and P₃ and valuesQ₁, Q₂, and Q₃ may be changed by the set of modulation schemes s₁(i),s₂(i), and s₃(i) (or need not be changed). Values P₁, P₂, and P₃ and/orvalues Q₁, Q₂, and Q₃ may be changed by the error correction codingmethod (such as the code length (block length) and the coding rate) (orneed not be changed).

Similarly, in FIGS. 53 and 54, the phase changing method may be changedby the set of modulation schemes s₁(i), s₂(i), and s₃(i) (or need not bechanged). The phase changing method may be changed by the errorcorrection coding method (such as the code length (block length) and thecoding rate) (or need not be changed).

FIGS. 55, 56, 57, and 58 will be described below. FIGS. 55, 56, 57, and58 are views illustrating a configuration example in which the precodingmethod is performed when average power of the three transmission signalsvaries and when the phase changing unit is newly added.

In FIG. 55, the component operating similarly to FIG. 53 is designatedby the identical reference mark. FIG. 55 differs from FIG. 53 in thatphase changing units 4901A, 4901B, and 4901C are added.

Phase changing unit 4901A receives baseband signal s₁(i) (4705A) andcontrol signal 4714 as input, and changes the phase of baseband signals₁(i) (4705A) based on control signal 4714. Accordingly, the post-phasechange signal of baseband signal s₁(i) (4705A) is expressed asC₁×e^(jω1(i))×s₁(i), and phase changing unit 4901A outputsC₁×e^(jω1(i))×s₁(t) as post-phase change signal 4902A (j may be animaginary unit, and C₁ may be 1.00 or a real number of 0 or more). Thevalue of the changed phase may be a function of i such as ω₁(i), or afixed value that is not the function of i.

Similarly, phase changing unit 4901B receives baseband signal s₂(i)(4705B) and control signal 4714 as input, and changes the phase ofbaseband signal s₂(i) (4705B) based on control signal 4714. Accordingly,the post-phase change signal of baseband signal s₂(i) (4705B) isexpressed as C₂×e^(jω2(i))×s₂(i), and phase changing unit 4901B outputsC₂×e^(jω2(i))×s₂(i) as post-phase change signal 4902B (j may be animaginary unit, and C₂ may be 1.00 or a real number of 0 or more). Thevalue of the changed phase may be a function of i such as ω₂(i), or afixed value that is not the function of i.

Similarly, phase changing unit 4901C receives baseband signal s₃(i)(4705C) and control signal 4714 as input, and changes the phase ofbaseband signal s₃(i) (4705C) based on control signal 4714. Accordingly,the post-phase change signal of baseband signal s₃(i) (4705C) isexpressed as C₃×e^(jω3(i))×s₃(i), and phase changing unit 4901C outputsC₃×e^(jω3(i))×s₃(i) as post-phase change signal 4902C (j may be animaginary unit, and C₃ may be 1.00 or a real number of 0 or more). Thevalue of the changed phase may be a function of i such as ω₃(i), or afixed value that is not the function of i.

The components subsequent to phase changing units 4901A, 4901B, and4901C operate similarly to the components in FIG. 53. Accordingly,z₁(i), z₂(i), and z₃(i) that are of the outputs of phase changing units4712A, 4712B, and 4712C in FIG. 55 are expressed by Equation (70).

[Mathematical  formula  70] $\begin{matrix}\begin{matrix}{\begin{pmatrix}{z_{1}(i)} \\{z_{2}(i)} \\{z_{3}(i)}\end{pmatrix} = {\begin{pmatrix}{y_{1}(i)} & 0 & 0 \\0 & {y_{2}(i)} & 0 \\0 & 0 & {y_{3}(i)}\end{pmatrix}\begin{pmatrix}Q_{1} & 0 & 0 \\0 & Q_{2} & 0 \\0 & 0 & Q_{3}\end{pmatrix}\begin{pmatrix}a_{11} & a_{12} & a_{13} \\a_{21} & a_{22} & a_{23} \\a_{31} & a_{32} & a_{33}\end{pmatrix} \times}} \\{{\begin{pmatrix}P_{1} & 0 & 0 \\0 & P_{2} & 0 \\0 & 0 & P_{3}\end{pmatrix}\begin{pmatrix}{C_{1} \times e^{j\; {{\omega 1}{(i)}}}} & 0 & 0 \\0 & {C_{2} \times e^{j\; {{\omega 2}{(i)}}}} & 0 \\0 & 0 & {C_{3} \times e^{j\; {{\omega 3}{(i)}}}}\end{pmatrix}\begin{pmatrix}{s_{1}(i)} \\{s_{2}(i)} \\{s_{3}(i)}\end{pmatrix}}} \\{= {\begin{pmatrix}{B_{1} \times e^{j\; {{\theta 1}{(i)}}}} & 0 & 0 \\0 & {B_{2} \times e^{j\; {{\theta 2}{(i)}}}} & 0 \\0 & 0 & {B_{3} \times e^{j\; {{\theta 3}{(i)}}}}\end{pmatrix}\begin{pmatrix}Q_{1} & 0 & 0 \\0 & Q_{2} & 0 \\0 & 0 & Q_{3}\end{pmatrix}\begin{pmatrix}a_{11} & a_{12} & a_{13} \\a_{21} & a_{22} & a_{23} \\a_{31} & a_{32} & a_{33}\end{pmatrix} \times}} \\{{\begin{pmatrix}P_{1} & 0 & 0 \\0 & P_{2} & 0 \\0 & 0 & P_{3}\end{pmatrix}\begin{pmatrix}{C_{1} \times e^{j\; {{\omega 1}{(i)}}}} & 0 & 0 \\0 & {C_{2} \times e^{j\; {{\omega 2}{(i)}}}} & 0 \\0 & 0 & {C_{3} \times e^{j\; {{\omega 3}{(i)}}}}\end{pmatrix}\begin{pmatrix}{s_{1}(i)} \\{s_{2}(i)} \\{s_{3}(i)}\end{pmatrix}}}\end{matrix} & {{Equation}\mspace{14mu} (70)}\end{matrix}$

FIG. 56 is a configuration diagram different from FIG. 55 in order toperform Equation (70). In FIG. 56, the component operating similarly tothat in FIG. 55 is designated by the identical reference mark.

FIG. 56 differs from FIG. 55 in a positional relationship between thephase changing unit and power changing unit that are located at thepreceding stage of weighting unit 4708. Accordingly, in FIG. 56, phasechanging unit 4901A exists at the subsequent stage of power changingunit 4706A, phase changing unit 4901B exists at the subsequent stage ofpower changing unit 4706B, and phase changing unit 4901C exists at thesubsequent stage of power changing unit 4706C.

Equation (71) holds because each component in FIG. 56 operates similarlyto each component in FIG. 50.

[Mathematical  formula  71] $\begin{matrix}\begin{matrix}{\begin{pmatrix}{z_{1}(i)} \\{z_{2}(i)} \\{z_{3}(i)}\end{pmatrix} = {\begin{pmatrix}Q_{1} & 0 & 0 \\0 & Q_{2} & 0 \\0 & 0 & Q_{3}\end{pmatrix}\begin{pmatrix}{y_{1}(i)} & 0 & 0 \\0 & {y_{2}(i)} & 0 \\0 & 0 & {y_{3}(i)}\end{pmatrix}\begin{pmatrix}a_{11} & a_{12} & a_{13} \\a_{21} & a_{22} & a_{23} \\a_{31} & a_{32} & a_{33}\end{pmatrix} \times}} \\{{\begin{pmatrix}P_{1} & 0 & 0 \\0 & P_{2} & 0 \\0 & 0 & P_{3}\end{pmatrix}\begin{pmatrix}{C_{1} \times e^{j\; {{\omega 1}{(i)}}}} & 0 & 0 \\0 & {C_{2} \times e^{j\; {{\omega 2}{(i)}}}} & 0 \\0 & 0 & {C_{3} \times e^{j\; {{\omega 3}{(i)}}}}\end{pmatrix}\begin{pmatrix}{s_{1}(i)} \\{s_{2}(i)} \\{s_{3}(i)}\end{pmatrix}}} \\{= {\begin{pmatrix}Q_{1} & 0 & 0 \\0 & Q_{2} & 0 \\0 & 0 & Q_{3}\end{pmatrix}\begin{pmatrix}{B_{1} \times e^{j\; {{\theta 1}{(i)}}}} & 0 & 0 \\0 & {B_{2} \times e^{j\; {{\theta 2}{(i)}}}} & 0 \\0 & 0 & {B_{3} \times e^{j\; {{\theta 3}{(i)}}}}\end{pmatrix}\begin{pmatrix}a_{11} & a_{12} & a_{13} \\a_{21} & a_{22} & a_{23} \\a_{31} & a_{32} & a_{33}\end{pmatrix} \times}} \\{{\begin{pmatrix}P_{1} & 0 & 0 \\0 & P_{2} & 0 \\0 & 0 & P_{3}\end{pmatrix}\begin{pmatrix}{C_{1} \times e^{j\; {{\omega 1}{(i)}}}} & 0 & 0 \\0 & {C_{2} \times e^{j\; {{\omega 2}{(i)}}}} & 0 \\0 & 0 & {C_{3} \times e^{j\; {{\omega 3}{(i)}}}}\end{pmatrix}\begin{pmatrix}{s_{1}(i)} \\{s_{2}(i)} \\{s_{3}(i)}\end{pmatrix}}}\end{matrix} & {{Equation}\mspace{14mu} (71)}\end{matrix}$

z₁(i) in Equation (70) is equal to z₁(i) in Equation (71), z₂(i) inEquation (70) is equal to z₂(i) in Equation (71), and z₃(i) in Equation(70) is equal to z₃(i) in Equation (71).

In FIGS. 55 and 56, post-power change values P₁, P₂, and P₃ and valuesQ₁, Q₂, and Q₃ may be changed by the set of modulation schemes s₁(i),s₂(i), and s₃(i) (or need not be changed). Values P₁, P₂, and P₃ and/orvalues Q₁, Q₂, and Q₃ may be changed by the error correction codingmethod (such as the code length (block length) and the coding rate) (orneed not be changed).

Similarly, in FIGS. 55 and 56, the phase changing method for both thepreceding and subsequent stages of weighting unit 4708 may be changed bythe set of modulation schemes s₁(i), s₂(i), and s₃(i) (or need not bechanged). The phase changing method may be changed by the errorcorrection coding method (such as the code length (block length) and thecoding rate) (or need not be changed).

In FIG. 57, the component operating similarly to FIG. 54 is designatedby the identical reference mark. FIG. 57 differs from FIG. 54 in thatphase changing units 4901A, 4901B, and 4901C are added.

Phase changing unit 4901A receives baseband signal s₁(i) (4705A) andcontrol signal 4714 as input, and changes the phase of baseband signals₁(i) (4705A) based on control signal 4714. Accordingly, the post-phasechange signal of baseband signal s₁(i) (4705A) is expressed asC₁×e^(jω1(i))×s₁(i), and phase changing unit 4901A outputsC₁×e^(jω1(i))×s₁(i) as post-phase change signal 4902A (j may be animaginary unit, and C₁ may be 1.00 or a real number of 0 or more). Thevalue of the changed phase may be a function of i such as ω₁(i), or afixed value that is not the function of i.

Similarly, phase changing unit 4901B receives baseband signal s₂(i)(4705B) and control signal 4714 as input, and changes the phase ofbaseband signal s₂(i) (4705B) based on control signal 4714. Accordingly,the post-phase change signal of baseband signal s₂(i) (4705B) isexpressed as C₂×e^(jω2(i))×s₂(i), and phase changing unit 4901B outputsC₂×e^(jω2(i))×s₂(i) as post-phase change signal 4902B (j may be animaginary unit, and C₂ may be 1.00 or a real number of 0 or more). Thevalue of the changed phase may be a function of i such as ω₂(i), or afixed value that is not the function of i.

Similarly, phase changing unit 4901C receives baseband signal s₃(i)(4705C) and control signal 4714 as input, and changes the phase ofbaseband signal s₃(i) (4705C) based on control signal 4714. Accordingly,the post-phase change signal of baseband signal s₃(i) (4705C) isexpressed as C₃×e^(jω3(i))×s₃(i), and phase changing unit 4901C outputsC₃×e^(jω3(i))×s₃(i) as post-phase change signal 4902C (j may be animaginary unit, and C₃ may be 1.00 or a real number of 0 or more). Thevalue of the changed phase may be a function of i such as ω₃(i), or afixed value that is not the function of i.

The components subsequent to phase changing units 4901A, 4901B, and4901C operate similarly to the components in FIG. 54. Accordingly,z₁(i), z₂(i), and z₃(i) that are of the outputs of phase changing units4712A, 4712B, and 4712C in FIG. 57 are expressed by Equation (72).

[Mathematical  formula  72] $\begin{matrix}\begin{matrix}{\begin{pmatrix}{z_{1}(i)} \\{z_{2}(i)} \\{z_{3}(i)}\end{pmatrix} = {\begin{pmatrix}{y_{1}(i)} & 0 & 0 \\0 & {y_{2}(i)} & 0 \\0 & 0 & {y_{3}(i)}\end{pmatrix}\begin{pmatrix}Q_{1} & 0 & 0 \\0 & Q_{2} & 0 \\0 & 0 & Q_{3}\end{pmatrix}\begin{pmatrix}a_{11} & a_{12} & a_{13} \\a_{21} & a_{22} & a_{23} \\a_{31} & a_{32} & a_{33}\end{pmatrix} \times}} \\{{\begin{pmatrix}{C_{1} \times e^{j\; {{\omega 1}{(i)}}}} & 0 & 0 \\0 & {C_{2} \times e^{j\; {{\omega 2}{(i)}}}} & 0 \\0 & 0 & {C_{3} \times e^{j\; {{\omega 3}{(i)}}}}\end{pmatrix}\begin{pmatrix}P_{1} & 0 & 0 \\0 & P_{2} & 0 \\0 & 0 & P_{3}\end{pmatrix}\begin{pmatrix}{s_{1}(i)} \\{s_{2}(i)} \\{s_{3}(i)}\end{pmatrix}}} \\{= {\begin{pmatrix}{B_{1} \times e^{j\; {{\theta 1}{(i)}}}} & 0 & 0 \\0 & {B_{2} \times e^{j\; {{\theta 2}{(i)}}}} & 0 \\0 & 0 & {B_{3} \times e^{j\; {{\theta 3}{(i)}}}}\end{pmatrix}\begin{pmatrix}Q_{1} & 0 & 0 \\0 & Q_{2} & 0 \\0 & 0 & Q_{3}\end{pmatrix}\begin{pmatrix}a_{11} & a_{12} & a_{13} \\a_{21} & a_{22} & a_{23} \\a_{31} & a_{32} & a_{33}\end{pmatrix} \times}} \\{{\begin{pmatrix}{C_{1} \times e^{j\; {{\omega 1}{(i)}}}} & 0 & 0 \\0 & {C_{2} \times e^{j\; {{\omega 2}{(i)}}}} & 0 \\0 & 0 & {C_{3} \times e^{j\; {{\omega 3}{(i)}}}}\end{pmatrix}\begin{pmatrix}P_{1} & 0 & 0 \\0 & P_{2} & 0 \\0 & 0 & P_{3}\end{pmatrix}\begin{pmatrix}{s_{1}(i)} \\{s_{2}(i)} \\{s_{3}(i)}\end{pmatrix}}}\end{matrix} & {{Equation}\mspace{14mu} (72)}\end{matrix}$

FIG. 58 is a configuration diagram different from FIG. 57 in order toperform Equation (72). In FIG. 58, the component operating similarly tothat in FIG. 57 is designated by the identical reference mark.

FIG. 58 differs from FIG. 57 in a positional relationship between thephase changing unit and power changing unit that are located at thepreceding stage of weighting unit 4708. Accordingly, in FIG. 58, phasechanging unit 4901A exists at the subsequent stage of power changingunit 4706A, phase changing unit 4901B exists at the subsequent stage ofpower changing unit 4706B, and phase changing unit 4901C exists at thesubsequent stage of power changing unit 4706C.

Equation (73) holds because each component in FIG. 58 operates similarlyto each component in FIG. 57.

[Mathematical  formula  73] $\begin{matrix}\begin{matrix}{\begin{pmatrix}{z_{1}(i)} \\{z_{2}(i)} \\{z_{3}(i)}\end{pmatrix} = {\begin{pmatrix}Q_{1} & 0 & 0 \\0 & Q_{2} & 0 \\0 & 0 & Q_{3}\end{pmatrix}\begin{pmatrix}{y_{1}(i)} & 0 & 0 \\0 & {y_{2}(i)} & 0 \\0 & 0 & {y_{3}(i)}\end{pmatrix}\begin{pmatrix}a_{11} & a_{12} & a_{13} \\a_{21} & a_{22} & a_{23} \\a_{31} & a_{32} & a_{33}\end{pmatrix} \times}} \\{{\begin{pmatrix}{C_{1} \times e^{j\; {{\omega 1}{(i)}}}} & 0 & 0 \\0 & {C_{2} \times e^{j\; {{\omega 2}{(i)}}}} & 0 \\0 & 0 & {C_{3} \times e^{j\; {{\omega 3}{(i)}}}}\end{pmatrix}\begin{pmatrix}P_{1} & 0 & 0 \\0 & P_{2} & 0 \\0 & 0 & P_{3}\end{pmatrix}\begin{pmatrix}{s_{1}(i)} \\{s_{2}(i)} \\{s_{3}(i)}\end{pmatrix}}} \\{= {\begin{pmatrix}Q_{1} & 0 & 0 \\0 & Q_{2} & 0 \\0 & 0 & Q_{3}\end{pmatrix}\begin{pmatrix}{B_{1} \times e^{j\; {{\theta 1}{(i)}}}} & 0 & 0 \\0 & {B_{2} \times e^{j\; {{\theta 2}{(i)}}}} & 0 \\0 & 0 & {B_{3} \times e^{j\; {{\theta 3}{(i)}}}}\end{pmatrix}\begin{pmatrix}a_{11} & a_{12} & a_{13} \\a_{21} & a_{22} & a_{23} \\a_{31} & a_{32} & a_{33}\end{pmatrix} \times}} \\{{\begin{pmatrix}{C_{1} \times e^{j\; {{\omega 1}{(i)}}}} & 0 & 0 \\0 & {C_{2} \times e^{j\; {{\omega 2}{(i)}}}} & 0 \\0 & 0 & {C_{3} \times e^{j\; {{\omega 3}{(i)}}}}\end{pmatrix}\begin{pmatrix}P_{1} & 0 & 0 \\0 & P_{2} & 0 \\0 & 0 & P_{3}\end{pmatrix}\begin{pmatrix}{s_{1}(i)} \\{s_{2}(i)} \\{s_{3}(i)}\end{pmatrix}}}\end{matrix} & {{Equation}\mspace{14mu} (73)}\end{matrix}$

z₁(i) in Equation (70), z₁(i) in Equation (71), z₁(i) in Equation (72),and z₁(i) in Equation (73) are equal to one another, z₂(i) in Equation(70), z₂(i) in Equation (71), z₂(i) in Equation (72), and z₂(i) inEquation (73) are equal to one another, z₃(i) in Equation (70), z₃(i) inEquation (71), z₃(i) in Equation (72), and z₃(i) in Equation (73) areequal to one another.

In FIGS. 57 and 58, post-power change values P₁, P₂, and P₃ and valuesQ₁, Q₂, and Q₃ may be changed by the set of modulation schemes s₁(i),s₂(i), and s₃(i) (or need not be changed). Values P₁, P₂, and P₃ and/orvalues Q₁, Q₂, and Q₃ may be changed by the error correction codingmethod (such as the code length (block length) and the coding rate) (orneed not be changed).

Similarly, in FIGS. 57 and 58, the phase changing method may be changedby the set of modulation schemes s₁(i), s₂(i), and s₃(i) (or need not bechanged). The phase changing method may be changed by the errorcorrection coding method (such as the code length (block length) and thecoding rate) (or need not be changed).

Accordingly, the present exemplary embodiment leads to the followingadvantageous effect. That is, there is a high possibility of improvingthe data reception quality, and particularly there is a high possibilityof largely improving the data reception quality in the LOS environmentin which the direct wave is dominant.

For example, the precoding matrix may be switched when the set ofmodulation schemes of the three streams is switched. The phase changingmethod may be switched when the set of modulation schemes of the threestreams is switched. The precoding matrix and the phase changing methodmay be switched when the set of modulation schemes of the three streamsis switched (the precoding matrix and the phase changing need not beswitched even if the set of modulation schemes of the three streams isswitched).

(Supplement 1)

The above exemplary embodiments and other contents may be combined.

The above exemplary embodiments and other contents are described only byway of example. For example, even if “the modulation scheme, the errorcorrection coding scheme (such as the error correction code, codelength, and coding rate used), and the control information” areillustrated, a similar configuration can also be embodied in the casethat “another modulation scheme, another error correction coding scheme(such as the error correction code, code length, and coding rate used),and another control information” are applied.

Even if a modulation scheme other than the modulation scheme describedin the exemplary embodiments is used, the exemplary embodiments andother contents can be performed. For example, APSK (Amplitude PhaseShift Keying) (such as 16APSK, 64APSK, 128APSK, 256APSK, 1024APSK, and4096APSK), PAM (Pulse Amplitude Modulation)(such as 4PAM, 8PAM, 16PAM,64PAM, 128PAM, 256PAM, 1024PAM, and 4096PAM), PSK (Phase Shift Keying)(such as BPSK, QPSK, 8PSK, 16PSK, 64PSK, 128PSK, 256PSK, 1024PSK, and4096PSK), and QAM (Quadrature Amplitude Modulation) (such as 4QAM, 8QAM,16QAM, 64QAM, 128QAM, 256QAM, 1024QAM, and 4096QAM) may be applied, orhomogeneous mapping or non-homogeneous mapping may be performed in eachmodulation scheme.

The method for disposing the 2, 4, 8, 16, 64, 128, 256, or 1024 signalpoints on the I-Q plane (the modulation scheme having the 2, 4, 8, 16,64, 128, 256, or 1024 signal points) is not limited to the signal pointdisposing method of the modulation scheme in the exemplary embodiments.Accordingly, the function of outputting the in-phase component and thequadrature component based on the plurality of bits becomes the functionof the mapping unit, and the performance of the precoding and phasechange becomes an effective function of the present disclosure.

When “∀” and “∃” exist in the specification, “∀” indicates a universalquantifier, and “∃” indicates an existential quantifier.

In the case that the complex plane exists in the specification, “radian”is used as a phase unit such as the argument.

The use of the complex plane can display a polar coordinate of thecomplex number in a polar form. Assuming that point (a,b) on the complexplane corresponds to complex number z=a+jb (a and b are a real number,and j is an imaginary unit), a=r×cos θ and b=r×sin θ are obtained whenpoint (a,b) is expressed by [r,θ] in terms of the polar coordinate, andEquation (74) holds.

r=√{square root over (a ² +b ²)}[Mathematical formula 74]

r is absolute value (r=|z|) of z, and θ is the argument. Therefore,z=a+jb is expressed by r×e^(jθ).

In the method of the exemplary embodiments, the transmission device doesnot transmit the direct information on the method for regularlyswitching the precoding matrix, but the reception device estimates theinformation on the preceding of “the method for regularly switching theprecoding matrix” used by the transmission device. Therefore, anadvantageous effect that the data transmission efficiency is improvedcan be obtained because the transmission device does not transmit thedirect information on the method for regularly switching the precodingmatrix.

In the method of the exemplary embodiments, the precoding weight changeis performed on the time axis. As described in the first exemplaryembodiment, the exemplary embodiments can similarly be performed even ifthe multi-carrier transmission method such as the OFDM transmission isused.

Particularly, when the precoding switching method is changed by thenumber of transmission signals, the reception device can recognize theprecoding switching method by obtaining the information on the number oftransmission signals transmitted by the transmission device.

In the specification, the reception device and antenna of the terminalmay separately be provided. For example, the reception device includesan interface to which the signal received by the antenna or the signalthat is received by the antenna and subjected to the frequencyconversion through a cable, and the reception device performs thesubsequent pieces of processing. The data and information obtained bythe reception device are converted into video and audio, and displayedon a monitor or output as sound from a speaker. The data and informationobtained by the reception device are subjected to signal processingrelated to the video and audio (need not be subjected to the signalprocessing), and may be output from an RCA terminal (a video terminaland an audio terminal) included in the reception device, a USB(Universal Serial Bus), an HDMI (registered trademark) (High-DefinitionMultimedia Interface), or a digital terminal.

In the specification, for example, it is considered that thetransmission device is included in communication and broadcastingdevices such as a broadcasting station, a base station, an access point,a terminal, and a mobile phone. At this point, it is considered that thereception device is included in communication devices such as atelevision receiver, a radio set, a terminal, a personal computer, amobile phone, an access point, and a base station. The transmissiondevice and reception device of the present disclosure have thecommunication function, and it is conceivable that the transmissiondevice and the reception device can be connected to a device, such as atelevision receiver, a radio set, a personal computer, and a mobilephone, which performs an application through some sort of interface.

In the exemplary embodiments, such the symbol other than the data symbolas a pilot symbol (such as a preamble, a unique word, a postamble, and areference symbol), and the symbol for the control information mayarbitrarily be disposed in the frame. In the exemplary embodiments, theterms of pilot symbol and the control information symbol are used.However, the terms may be called in any way, and the function of itselfis important.

For example, in the transmitter and the receiver, the pilot symbol maybe an already-known symbol modulated by the PSK modulation (or thereceiver may synchronize to recognize the symbol transmitted by thetransmitter), and the receiver performs frequency synchronization, timesynchronization, channel estimation (of each modulated signal)(estimation of CSI (Channel State Information)), and signal detectionusing the symbol.

The control information symbol is used to transmit information (such asthe modulation scheme, the error correction coding scheme, and thecoding rate of the error correction coding scheme, which are used in thecommunication, and setting information on an upper layer) that needs tobe transmitted to the a communication partner in order to perform thecommunication except for the data (for example, the application).

The present disclosure is not limited to the above exemplaryembodiments, but various changes can be made. For example, the exemplaryembodiments are described when performed as the communication device.Alternatively, the communication method may be performed as software.

The precoding switching method is described above in the method fortransmitting the two modulated signals from the two antennas.Additionally, the precoding switching method for changing the precodingweight (matrix) can similarly be performed in a method for performingthe precoding on the four post-mapping signals, generating the fourmodulated signals, and transmitting the four modulated signals from thefour antennas, namely, a method for performing the precoding on Npost-mapping signals, generating N modulated signals, and transmittingthe N modulated signals from N antennas.

In the present disclosure, the terms such as “precoding” and “precodingweight” are used. However, the terms may be called in any way. In thepresent disclosure, the signal processing of itself is important.

The different pieces of data may be transmitted using streams s₁(t) ands₂(t), or the identical data may be transmitted using streams s₁(t) ands₂(t).

For both the transmit antenna of the transmission device and the receiveantenna of the reception device, one antenna illustrated in the drawingmay be constructed with a plurality of antennas.

It is necessary for the transmission device to post the transmissionmethod (the MIMO, the SISO, the time and space block coding, and theinterleaving scheme), the modulation scheme, and the error correctioncoding scheme to the reception device. However, this point is omitted inthe exemplary embodiments. A posting signal exists in the frametransmitted by the transmission device. The reception device obtains theposting signal to change the operation.

For example, a program executing the communication method is previouslystored in a ROM (Read Only Memory), and the program may be operated by aCPU (Central Processor Unit).

The program executing the communication method is stored in acomputer-readable storage medium, the program stored in the storagemedium is recorded in a RAM (Random Access Memory) of a computer, andthe computer may be operated according to the program.

Each of the configurations of the exemplary embodiments may typically beconstructed with an LSI (Large Scale Integration) of an integratedcircuit including an input terminal and an output terminal. Theconfigurations of the exemplary embodiments may individually be formedinto one chip, or a whole or part of the configuration of each exemplaryembodiment may be formed into one chip. At this point, the term of theLSI is used. Sometimes an IC (Integrated Circuit), a system LSI, a superLSI, and an ultra LSI are used depending on a degree of integration. Anintegrated circuit technique is not limited to the LSI, but theintegrated circuit may be made by a dedicated circuit or ageneral-purpose processor. An FPGA (Field Programmable Gate Array) thatcan be programmed after LSI production or a reconfigurable processor inwhich connection and setting of a circuit cell in the LSI may be used.

When an integrated circuit technology that replaces the LSI therewithemerges with the progress of a semiconductor technology or a derivativetechnology, a functional block may be integrated using the integratedcircuit technology. A biotechnology may be applied.

(Supplement 2)

In the first, second, third, and fourth exemplary embodiments, the phasechange is mainly performed after the precoding. Modifications of thephase change will be described below.

In Equation (60) of the third exemplary embodiment, post-power changevalues P₁, P₂, P₃, and P₄ may be switched time to a function of “time”,“frequency”, or “time and frequency”, namely, post-power change valuesP₁, P₂, P₃, and P₄ may be switched to “time”, “frequency”, or “time andfrequency”.

In the third exemplary embodiment, post-power change values P₁, P₂, P₃,and P₄ in Equation (61), post-power change values P₁, P₂, P₃, and P₄ inEquation (62), post-power change values P₁, P₂, P₃, and P₄ in Equation(63), post-power change values P₁, P₂, P₃, and P₄ in Equation (64),post-power change values P₁, P₂, P₃, and P₄ in Equation (65), andpost-power change values P₁, P₂, P₃, and P₄ in Equation (66) may beswitched time to a function of “time”, “frequency”, or “time andfrequency”, namely, post-power change values P₁, P₂, P₃, and P₄ inEquation (61), post-power change values P₁, P₂, P₃, and P₄ in Equation(62), post-power change values P₁, P₂, P₃, and P₄ in Equation (63),post-power change values P₁, P₂, P₃, and P₄ in Equation (64), post-powerchange values P₁, P₂, P₃, and P₄ in Equation (65), and post-power changevalues P₁, P₂, P₃, and P₄ in Equation (66) may be switched time to“time”, “frequency”, or “time and frequency”.

In the third exemplary embodiment, post-power change values Q₁, Q₂, Q₃,and Q₄ in Equation (61), post-power change values Q₁, Q₂, Q₃, and Q₄ inEquation (62), post-power change values Q₁, Q₂, Q₃, and Q₄ in Equation(63), post-power change values Q₁, Q₂, Q₃, and Q₄ in Equation (64),post-power change values Q₁, Q₂, Q₃, and Q₄ in Equation (65), andpost-power change values Q₁, Q₂, Q₃, and Q₄ in Equation (66) may beswitched time to a function of “time”, “frequency”, or “time andfrequency”, namely, post-power change values Q₁, Q₂, Q₃, and Q₄ inEquation (61), post-power change values Q₁, Q₂, Q₃, and Q₄ in Equation(62), post-power change values Q₁, Q₂, Q₃, and Q₄ in Equation (63),post-power change values Q₁, Q₂, Q₃, and Q₄ in Equation (64), post-powerchange values Q₁, Q₂, Q₃, and Q₄ in Equation (65), and post-power changevalues Q₁, Q₂, Q₃, and Q₄ in Equation (66) may be switched time to“time”, “frequency”, or “time and frequency”.

In Equation (67) of the fourth exemplary embodiment, post-power changevalues P₁, P₂, and P₃ may be switched time to a function of “time”,“frequency”, or “time and frequency”, namely, post-power change valuesP₁, P₂, and P₃ may be switched by “time”, “frequency”, or “time andfrequency”.

In the fourth exemplary embodiment, post-power change values P₁, P₂, andP₃ in Equation (68), post-power change values P₁, P₂, and P₃ in Equation(69), post-power change values P₁, P₂, and P₃ in Equation (70),post-power change values P₁, P₂, and P₃ in Equation (71), post-powerchange values P₁, P₂, and P₃ in Equation (72), and post-power changevalues P₁, P₂, and P₃ in Equation (73) may be switched time to afunction of “time”, “frequency”, or “time and frequency”, namely,post-power change values P₁, P₂, and P₃ in Equation (68), post-powerchange values P₁, P₂, and P₃ in Equation (69), post-power change valuesP₁, P₂, and P₃ in Equation (70), post-power change values P₁, P₂, and P₃in Equation (71), post-power change values P₁, P₂, and P₃ in Equation(72), and post-power change values P₁, P₂, and P₃ in Equation (73) maybe switched time to “time”, “frequency”, or “time and frequency”.

In the fourth exemplary embodiment, post-power change values Q₁, Q₂, andQ₃ in Equation (68), post-power change values Q₁, Q₂, and Q₃ in Equation(69), post-power change values Q₁, Q₂, and Q₃ in Equation (70),post-power change values Q₁, Q₂, and Q₃ in Equation (71), post-powerchange values Q₁, Q₂, and Q₃ in Equation (72), and post-power changevalues Q₁, Q₂, and Q₃ in Equation (73) may be switched time to afunction of “time”, “frequency”, or “time and frequency”, namely,post-power change values Q₁, Q₂, and Q₃ in Equation (68), post-powerchange values Q₁, Q₂, and Q₃ in Equation (69), post-power change valuesQ₁, Q₂, and Q₃ in Equation (70), post-power change values Q₁, Q₂, and Q₃in Equation (71), post-power change values Q₁, Q₂, and Q₃ in Equation(72), and post-power change values Q₁, Q₂, and Q₃ in Equation (73) maybe switched time to “time”, “frequency”, or “time and frequency”.

The present disclosure can widely be applied to the wireless system thattransmits different modulated signals from the plurality of antennas.The present disclosure can also be applied to the case that the MIMOtransmission is performed in the wired communication system includingthe plurality of transmission points (such as a PLC (Power LineCommunication) system, an optical communication system, and a DSL(Digital Subscriber Line) system).

The following items are included in various aspect of the exemplaryembodiments of the present disclosure.

According to a first aspect of the present disclosure, a transmissiondevice includes: a weighting circuitry which, in operation, generatestransmission signals of n streams (n is an integer of 3 or more) byweighting modulated signals of the n streams using a predetermined fixedprecoding matrix; a phase changing circuitry which, in operation,regularly changes each phase of a symbol series included in each of thetransmission signals of the n streams; and a transmitter circuitrywhich, in operation, transmits the transmission signals of the n streamsfrom different antennas, the phases of each of the transmission signalsof the n streams being changed in each symbol. At this point, thetransmission signal of an i-th stream has an m_(i) kind of phase changevalue y_(i)(t) (i is an integer between 1 and n (inclusive), 0≤y_(i)<2π,and m_(i) is set in each stream, t is an integer of 0 or more, andindicates a symbol slot), and the phase changing circuitry changes thephase in one or more u (u=m₁×m₂× . . . ×m_(n)) symbol periods using allpatterns of a set of phase change values y_(i)(t) different from eachother in each symbol.

According to a second aspect of the present disclosure, in thetransmission device of the first aspect, at least one of thetransmission signals of the n streams has one kind of phase change valuey_(i)(t).

According to a third aspect of the present disclosure, in thetransmission device of the first aspect, at least one of thetransmission signals of the n streams has 0 radian of phase change valuey_(i)(t).

According to a fourth aspect of the present disclosure, in thetransmission device of the first aspect, the phase change value y₁(t) ofthe transmission signal of a first stream includes at least one phasechange value equal to the phase change value y₂(t) of the transmissionsignal of a second stream.

According to a fifth aspect of the present disclosure, a transmissionmethod includes: generating transmission signals of n streams (n is aninteger of 3 or more) by weighting modulated signals of the n streamsusing a predetermined fixed precoding matrix; changing regularly eachphase of a symbol series included in each of the transmission signals ofthe n streams; and transmitting the transmission signals of the nstreams from different antennas, the phases of each of the transmissionsignals of the n streams being changed in each symbol. At this point,the transmission signal of an i-th stream has an m_(i) kind of phasechange value y_(i)(t) (i is an integer between 1 and n (inclusive),0<y_(i)<2π, and m_(i) is set in each stream, t is an integer of 0 ormore, and indicates a symbol slot), and the phase change is performed inone or more u (u=m₁×m₂× . . . ×m_(n)) symbol periods using all patternsof a set of phase change values y_(i)(t) different from each other ineach symbol. According to a sixth aspect of the present disclosure, inthe transmission method of the fifth aspect, at least one of thetransmission signals of the n streams has one kind of phase change valuey_(i)(t).

According to a seventh aspect of the present disclosure, in thetransmission method of the fifth aspect, at least one of thetransmission signals of the n streams has 0 radian of the phase changevalue y_(i)(t).

According to an eighth aspect of the present disclosure, in thetransmission method of the fifth aspect, the phase change value y₁(t) ofthe transmission signal of a first stream includes at least one phasechange value equal to the phase change value y₂(t) of the transmissionsignal of a second stream.

The present disclosure can widely be applied to a wireless system thattransmits different modulated signals from the plurality of antennas,for example, suitably applied to the OFDM-MIMO communication system. Thepresent disclosure can also be applied to the case that the MIMOtransmission is performed in the wired communication system includingthe plurality of transmission points (such as a PLC (Power LineCommunication) system, an optical communication system, and a DSLDigital Subscriber Line) system). At this point, the plurality ofmodulated signals described in the present disclosure are transmittedusing the plurality of transmission points. The modulated signal may betransmitted from a plurality of transmission points.

What is claimed is:
 1. A transmission device comprising: precodingcircuitry which, in operation, generates precoding signals of a first toa fourth streams by precoding signals of the first to the fourth streamsusing a determined fixed precoding matrix, each of the signals of thefirst to fourth stream including a plurality of symbols; phase changingcircuitry which, in operation, regularly phase changes each of theplurality of symbols included in at least one of the precoding signalsof the second to the fourth streams by using M phase changing values, Mbeing an integer of 2 or more; OFDM transform circuitry which, inoperation, transforms each of the precoding signal of the first streamand the phase-changed transmission signals of the second to fourthstreams to first to fourth OFDM signals; and transmitter which, inoperation, transmits each of the first to fourth OFDM signals fromdifferent transmission antennas.
 2. The transmission device according toclaim 1, wherein the phase change circuitry continuously changes eachM×M symbols in at least two precoding signals of the second to fourthstreams by using the M phase change values to be changed each M symbols.3. The transmission device according to claim 1, wherein at least two ofthe precoding signals of the second to fourth streams are phase changedusing the same phase change value.
 4. A transmission method comprising:generating precoding signals of a first to a fourth streams by precodingsignals of the first to the fourth streams using a determined fixedprecoding matrix, each of the signals of the first to fourth streamincluding a plurality of symbols; phase changing regularly each of theplurality of symbols included in at least one of the precoding signalsof the second to the fourth streams by using M phase changing values, Mbeing an integer of 2 or more; transforming each of the precoding signalof the first stream and the phase-changed transmission signals of thesecond to fourth streams to a first to a fourth OFDM signals; andtransmitting each of the first to fourth OFDM signals from differenttransmission antennas.
 5. The transmission method according to claim 4,wherein at least two of precoding signals of the second to fourthstreams are continuously changed each M×M symbols by using the M phasechange values to be changed each M symbols.
 6. The transmission methodaccording to claim 4, wherein at least two of the precoding signals ofthe second to fourth streams are phase changed using the same phasechange value.
 7. A reception device comprising: reception circuitrywhich, in operation, receives four OFDM signals multiplexed with a firstto a fourth OFDM signals from a transmitting device by four receptionantennas respectively; and decoding circuitry which, in operation,decodes each of the first to the fourth OFDM signals to signals of thefirst to the fourth streams, wherein a process in which the first to thefourth OFDM signals is generated from the signals of the first to thefourth streams at the transmitting device includes: generating precodingsignals of the first to the fourth streams by precoding the signals ofthe first to the fourth streams using a determined fixed precodingmatrix, each of the signals of the first to fourth stream including aplurality of symbols; phase changing regularly each of the plurality ofsymbols included in at least one of the precoding signals of the secondto the fourth streams by using M phase changing values, M being aninteger of 2 or more; transforming each of the precoding signal of thefirst stream and the phase-changed transmission signals of the second tofourth streams to the first to the fourth OFDM signals; and transmittingeach of the first to fourth OFDM signals from different transmissionantennas.
 8. The reception device according to claim 7, wherein at leasttwo of precoding signals of the second to fourth streams arecontinuously changed each M×M symbols by using the M phase change valuesto be changed each M symbols.
 9. The reception device according to claim7, wherein at least two of the precoding signals of the second to fourthstreams are phase changed using the same phase change value.
 10. Areception method comprising: receiving four OFDM signals multiplexedwith a first to a fourth OFDM signals from a transmitting device by thefour reception antennas respectively; and decoding each of the first tothe fourth OFDM signals to signals of the first to the fourth streams,wherein a process in which the first to the fourth OFDM signals isgenerated from the signals of the first to the fourth streams at thetransmitting device includes: generating precoding signals of the firstto the fourth streams by precoding the signals of the first to thefourth streams using a determined fixed precoding matrix, each of thesignals of the first to fourth stream including a plurality of symbols;phase changing regularly each of the plurality of symbols included in atleast one of the precoding signals of the second to the fourth streamsby using M phase changing values, M being an integer of 2 or more;transforming each of the precoding signal of the first stream and thephase-changed transmission signals of the second to fourth streams tothe first to the fourth OFDM signals; and transmitting each of the firstto fourth OFDM signals from different transmission antennas.
 11. Thereception method according to claim 10, wherein at least two ofprecoding signals of the second to fourth streams are continuouslychanged each M×M symbols by using the M phase change values to bechanged each M symbols.
 12. The reception method according to claim 10,wherein at least two of the precoding signals of the second to fourthstreams are phase changed using the same phase change value.